scripts: seperate output dirs, improved logging, filename handling.

These changes might brake some other scripts.

Tested:

eoatex2pdf.py: works
eoatex2imxml.py: works, but needs `./bibformat` (not in repo)
imxml2django.py: works
imxml2epub.py: broken (propably is has been broken before?)

Problems: `./bibformat/` is needed but not in the repo. It can be
downloaded from NextCloud.

Improvements:

- scripts automatically enable the right latex preamble
  - remark: no preamble should be in the '.tex' file
- improved command line interface
- improved output to terminal and log files
- scripts output files into seperate folders