This ensures that we use a consistent Python interpreter in LyX.
$${python} is replaced by the Python version found.
Users can apply this in preferences and use the same version defined by
LyX.
The fixes are simple and on line with the changes made during
the 2.3 development. It was an oversight to leave them out.
With this commit all the python scripts should be supported by
python 2 and 3.
Fedora ships these chmod 644 and has never seen a problem. The advantage
to doing this is that it better controls what version of python we are
using to launch the script, and it will reveal if we're somehow somewhere
not controlling that properly.
