added first version to find and store neighbours of all elements during mesh initialisation (work in progress)

added some small helper functions (face normal calculation, on-surface-check, etc.), renamed MshElemType::LINE to EDGE, changed a bit of documentation

added recent changes concerning the attachment of time series sensor data to station objects from ogs5 to ogs6, added RapidXml as a small library for reading XML files from console application, added existing xml schema files

This reverts commit 05677165.

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

- removed method write()

- added template classes Grid and OctTree for efficiently searching in point sets

removed

added XmlIO; added FemEnums + Info-objects; added ProjectData; currently compile errors due to changes in PointVec

renamed namespace GEOLIB to GeoLib in order to be consistent with other OGS-libraries and directory names

- renamed method to access coordinates from getData() to getCoords()

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

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

- binarySearch
- class CPUTime
- class RunTime
- methods/functions from DateTools.{h,cpp}

changes in GeoLib and in SimpleTests folder results from changing the namespace

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

changed size_t to unsigned; included a few (yet unimplemented) methods for mesh-consistency checking

- 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