Substituted assert using exception. Added docu.

Using std::invalid_argument exception instead of assert leads to
error messages both in release and debug version.
Added exception to handle invalid input and docu.

Added exception std::invalid_argument to constructor of class template TemplateVec.
Made documentation more specific.
In PointVec::makePntsUnique simplify removing nullptr in pnt_vec.

Conflicts:
	GeoLib/PointVec.cpp
Removed call by ref in PointVec::makePntsUnique().
replaced vtkPolygons with vtkTriangles for geometric surface visualisation
Merge pull request #109 from TomFischer/ImproveGeoLibPointVec

Improve GeoLib::PointVec.
removed unused method-definitions and fixed enum mismatch
Merge branch 'master' of https://github.com/ufz/ogs
removed changes due to modified makepntsunique method
fixed warning
changed layer thickness information for mesh layer mapping from array to vector
Made MatrixBase a base class of (dense) matrix.
Merge pull request #111 from TomFischer/MathLibDenseMatrixInheritanceStructure

Made MatrixBase a base class of (dense) matrix MathLib::Matrix.