Update documentation.

Extend the input to arbitrary TemplatePoint,
but it is working only for TemplatePoint<double, 3>
== Point3d for now.

The lexicographic comparison is now working for
arbitrary TemplatePoint dimensions and underlying
floating types.

... into TemplatePoint header file.

Using the removed constructor was insecure because there was neither a
compile time check nor a run time check if the size of the C array holds
enough data.

Try to fix some failing tests on travis CI for Vector3 associated to default constructor of Vecor3.

Changed also
- the data type that holds the coordinates from pure C array to std::array<T, DIM>,
- the implementation of write() and read().

- Implemented class template GeoPoint (see GeoLib/Point.h) and substituted class templates in the typedef.
- Some changes due to changed namespace in MathLib/Vector3.h and GeoLib/Color.h.

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

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()

- 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