The classes ProjectorShell and ProjectorGroup are now defined in
different source files. This makes 'plotools.py' only contain
routines that control the data flows, including consistency checks
and output.
Originally, the tests worked only when run from their respective
directory. If one tries to run them from another directory (which happens
when test discovery is used) the tests were not able to find the input files.
Now, a dummy module 'rpath' is added to all tests whose sole role is
to obtain the current path.
The files from the original vasp-interface repository are reshuffled in
accord with the directory structure of dft_tools. Some of the directories,
such as 'test' (unit tests for the interface), 'examples' (simple examples for
the development purposes) are temporarily placed into 'python/vasp' directory
to avoid confusion with integral tests and examples of dft_tools.
