In cases when the underlying element is quadratic but the shape function
is of linear order, there is a dimension mismatch between the
NodalVectorType and the return value of the getNodalValuesOnElement.

Taking the first rows of the return matrix ensures correct dimensions.

These are almost the same and the difference is in the
handling of the shape functions.

-renaming from dependant to dependent
-documentation updated
-renaming from prefac to coefficient
-removed storage of local rhs in assembler

-new class for vdbc added, including 3 files and small changes in CreateBoundaryCondition.cpp