Improve parameter evaluation in Neumanntype boundary condition

Feature description was added to the changelog 
Tests covering your feature were added?  reference files for existing tests are updated
For every changed benchmark the analytical solution (as described in the prjfile) was generated. Then vtkdiff
was used for comparisons of computed solution with analytical solution. Here are some results:
Benchmark 2D_HeatConduction_wedge
Improved Neumann Evaluation
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/wedge_ang_0.02_ts_10_t_1.000000_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/wedge_ang_0.02_ts_10_t_1.000000_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [1.277802600374363e+00]
abs l2norm^2 = [1.147061848691392e02]
abs l2norm = [1.071009733238402e01]
abs maximum norm = [1.649954514900666e02]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Current Master
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/wedge_ang_0.02_ts_10_t_1.000000_master_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/wedge_ang_0.02_ts_10_t_1.000000_master_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [1.753154520925763e+00]
abs l2norm^2 = [2.302234454939754e02]
abs l2norm = [1.517311587954087e01]
abs maximum norm = [2.111845465255369e02]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Benchmark SteadyStateDiffusion_square_1x1_1e2_axi
Improved Neumann Evaluation
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/square_1e2_axi_ts_1_t_1.000000_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/square_1e2_axi_ts_1_t_1.000000_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [9.211672948918542e01]
abs l2norm^2 = [1.181201970720864e02]
abs l2norm = [1.086831160172022e01]
abs maximum norm = [2.078181092561411e02]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Current Master
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/square_1e2_axi_ts_1_t_1.000000_master_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/square_1e2_axi_ts_1_t_1.000000_master_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [1.253254043295376e+00]
abs l2norm^2 = [2.282820517187984e02]
abs l2norm = [1.510900564957199e01]
abs maximum norm = [2.677375737428922e02]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Benchmark SteadyStateDiffusion_square_1x1_1e4_axi_ang_0.02
Improved Neumann Evaluation
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/square_1e4_axi_ts_1_t_1.000000_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/square_1e4_axi_ts_1_t_1.000000_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [7.778561233344679e01]
abs l2norm^2 = [9.754565697524973e05]
abs l2norm = [9.876520489284155e03]
abs maximum norm = [2.450820612146307e04]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Current Master
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/square_1e4_axi_ts_1_t_1.000000_master_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/square_1e4_axi_ts_1_t_1.000000_master_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [1.050565421970479e+00]
abs l2norm^2 = [1.861052118723456e04]
abs l2norm = [1.364203840605742e02]
abs maximum norm = [3.048876172027878e04]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Benchmark SteadyStateDiffusion_wedge_1e2_ang_0.02
Improved Neumann Evaluation
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/wedge_ang_0.02_ts_10_t_1.000000_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/wedge_ang_0.02_ts_10_t_1.000000_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [1.277802600374363e+00]
abs l2norm^2 = [1.147061848691392e02]
abs l2norm = [1.071009733238402e01]
abs maximum norm = [1.649954514900666e02]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Current Master
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/wedge_ang_0.02_ts_10_t_1.000000_master_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/wedge_ang_0.02_ts_10_t_1.000000_master_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [1.753154520925763e+00]
abs l2norm^2 = [2.302234454939754e02]
abs l2norm = [1.517311587954087e01]
abs maximum norm = [2.111845465255369e02]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Benchmark SteadyStateDiffusion_wedge_1e4_ang_0.02
Improved Neumann Evaluation
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/wedge_1e4_axi_ang_0.02_ts_1_t_1.000000_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/wedge_1e4_axi_ang_0.02_ts_1_t_1.000000_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [1.532213755200179e+00]
abs l2norm^2 = [1.701154950494929e04]
abs l2norm = [1.304283309137600e02]
abs maximum norm = [2.203274695519564e04]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.
Current Master
fischeth@modmon107 ~/w/o/build/release % vtkdiff a temperature b analytical_solution /tmp/wedge_1e4_axi_ang_0.02_ts_1_t_1.000000_master_with_analytical_solution.vtu
Comparing data array `temperature' from file `/tmp/wedge_1e4_axi_ang_0.02_ts_1_t_1.000000_master_with_analytical_solution.vtu' to data array `analytical_solution' from file `'.
Computed difference between data arrays:
abs l1 norm = [2.991233405130929e+00]
abs l2norm^2 = [7.410801202299059e04]
abs l2norm = [2.722278678294906e02]
abs maximum norm = [3.650811207507661e04]
rel l1 norm = [inf]
rel l2norm^2 = [inf]
rel l2norm = [inf]
rel maximum norm = [inf]
Absolute and relative error (maximum norm) are larger than the corresponding thresholds 2.220446049250313e16 and 2.220446049250313e16.