changed dropFileExtension() implementation

Calling getFileNameFromPath() for now.

moved functions getFileNameFromPath(), getSuffixFromPath(), copyPathToFileName() and extractPath() from files StringTools.{cpp,h} to files FileTools.{cpp,h}

- remove functions to manipulate file names because they exist in StringTools.h
- move implementations into cpp
- fix type, etc.

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

in order to make the name of libraries, namespaces and directories more consistent the Base directory is know named BaseLib

- added test programm for solving a linear system with CG-method
- time measurement is at the moment OS dependent!
- added Base folder
- added GeoLib folder
- added files in MathLib folder - restructured MathLib folder