- added (a not yet finished version) CollapseMeshNodes programme
- changes in SimpleTests/MeshTests/CMakeLists.txt

[MeshCoarsener]
- new class used by CollapseMeshNodes
- can be used to make mesh nodes unique within a small epsilon radius

[MeshIO]
- added writing functionality for old mesh format

[GeoLib::Grid]
- changed interface (method getPointsWithinCube() -> getVecsOfGridCellsIntersectingCube())
- corrected documentation

[all mesh elements]
- added method clone()
- added method getType()
- removed attribute type from abstract base class Element

This reverts commit 05677165.

Conflicts:
	FileIO/XmlIO/XmlGspInterface.cpp
	README.md

- FileFinder.h
- FileTools.h
- TimeMeasurementBase.h
- quicksort.h

changes due to namespace changes in:
- PointVec.cpp
- Polygon.cpp
- AdjMat.cpp
- CRSMatrixReordered.cpp

implemented new class CRSMatrixReorderedOpenMP which uses Nested Dissection reordering and OpenMP for matrix vector multiplication

added more documentation to quicksort
added class CRSMatrixReordered
first version of nested dissection based on metis is now working

added another version of quicksort algorithm
corrected documentation in class SparseMatrixBase