Pythontex ebuild

Pythontex allows you to integrate python code into your LaTeX documents. It is especially relevant for open, transparent, reproducible, and live science/technology publishing - as it allows you to automatically regenerate graphics when your underlying data or analysis scripts change (as determined implicitly via a checksum).

The ebuild works quite nicely on my laptop, but not on my desktop computer (for some reason). On my desktop computer my terminal cannot properly access the paths to the modules

```shell
chymera@desktophost ~/wip $ pythontex.py demo.tex
bash: pythontex.py: command not found
chymera@desktophost ~/wip $ source /etc/profile
chymera@desktophost ~/wip $ source ~/.bashrc 
chymera@desktophost ~/wip $ pythontex.py demo.tex
Traceback (most recent call last):
  File "/usr/lib/python-exec/python2.7/pythontex.py", line 62, in <module>
    from pythontex_engines import *
ImportError: No module named pythontex_engines
```