The change is only relevant to development as all the call to python scripts is done
calling C++ os::python that invoques the appropriate python version.
The change is two fold, on one hand remove all the uses of /usr/bin/env for python.
On the other hand rename all the calls to python from python to python3 making it explicit
and being compliant with PEP 394 -- The "python" Command on Unix-Like Systems:
https://www.python.org/dev/peps/pep-0394/
Remove the sheebang from src/graphics/GraphicsConverter.cpp because it is not necessary.
Some small whitespace changes.
'cat.py' created by Richard Heck
This script resembles the unix command 'cat', valid now on every
platform.
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@34828 a592a061-630c-0410-9148-cb99ea01b6c8
