debug doc project

conf.py:

This file was completely rewritten for the purpose of getting Sphinx to accept
the restructured and renamed project. I simply wasn't able to figure out what
things would have been required to change to get Sphinx to understand the
structural changes.

Makefile:

 * Added automatical apidoc coverage. The manual way might have been more
   beautiful, but also meant a lot of manual maintenance, which we try to avoid
   at the moment.
 * made sure that the `clean:` task also cleans automatically generated api doc
   files
 * made `latexpdf:` and `html:` tasks require `clean` and `apidoc` for a
   complete rebuild of these parts.
 * add a task `all:` which builds html and latexpdf automatically

index.rst:
 * included the files generated by apidoc
 * changed one headline markup

pictures:
 * moved to _static folder
 * gif changed to png, because latexpdf doesn't seem to handle gif at all

Others:
 * some small changes, like renaming of :term: values

See #37 for more details.

Signed-off-by: Erik Bernoth <bernoth@dresearch-fe.de>