Integration of GromosXX and GromosPP into the repository

[RiesBen]

It would be awesome if we could integrate the source code of GromosXX/PP as submodules to the PyGromosTools package, such that users could get all in one and the integration of the packages would be significantly easier! :)

ToDos:

• Integrate packages as submodules.
• Compile packages with anaconda script. ( https://anaconda.org/anaconda/automake, https://anaconda.org/conda-forge/gcc)
• consider program PyBinding with SWIG - an automatic API Tool. (http://www.swig.org/) - not optimal but efficient / alternative: PyBinds11 - but requires Cmake

Advantages:

• All code can be retrieved from one package, but no git- or package structure needs to be changed.
• Code management can work in separated packages - no invasiv
• Help user compiling of gromos with standardized anaconda tools
• Allow tighter integration of Gromos

[RiesBen]

Another aspect: if the files would be integrated, we could use the docstring information from GromsXX and GromosPP to update the pygromosDocsstrings automatically. (so we do not need to update two sources)

[RiesBen]

And we could keep only one ene_ana_lib ;)