This saves 16% of instructions in the
GroundwaterFlow::init() code due to faster access
in the multi-index table.

In the conversion of a vtkUnstructuredGrid replace
the 5*(nr of elements) GetCell() calls with vtk's
provided function.

The 5*(nr of elements) GetCell() calls make around
50% of total instruction spent in
convertUnstructuredGrid().

For current groundwater flow simulation without the
linear solver call it makes around 1/6 of total
instructions.

GMSH2OGS add switch for writing line elements.

Vtk result output; vtkdiff

The result is written into a new or an existing
mesh's PropertyVector.

Mesh object is unfortunately modified, therefor the
const specifier is omited.

Using VtuInterface to write the mesh, which will
hold the resulting data in a PropertyVector.

Remove writing to an output stream.

Cleanup

Carry out the double arithmetics until the index access, which is checked for conversion.

Fixed two more warnings

[Fix] Solving several issues concerned with mesh mapping using raster files

fix compiler warnings C4800 with MSVC

Fixing warnings

module load lis/1.5.54_gcc-4.8.1-3

Initialize with zeros in TemplatePoint default constructor

[GeoLib] Restructure and bug fix.

- early return in case of an error
- reworked loop structure a little bit

- j++ -> j++, k++ -> ++k,
- added nullptr check,
- using make_pair,
- moved fetching the PointVec object from inner loop.