merged unstable into py3
* include the major changes of a94f8ed94280ed8bfa7c46b8f811aa402d7c8981
of blockstructure.py
* adapted all code to python 3
* fixed all tests
* moved the plovasp C++ code to c++/triqs_dft_tools/converters/vasp
* added global header triqs_dft_tools/triqs_dft_tools.hpp
* python dir based on single cmakelist file
* registered C++ tests for plovasp
* corrected imports for py3 tests for plovasp
* corrected block order in sigma_from_file and srvo3_Gloc
* exchanged ref files for sigma_from_file, srvo3_Gloc, SrVO3.ref.h5
* moved vasp converter bash scripts from dir shells to bin dir
