- moved files in proper directories and adapted paths where needed
- deleted doc/oldbugs.txt (asked confirmation to jesterking a week ago in irc)
- still working on doxygen files, for now I'll leave them in doc/
- NOTE: while checking if other files were referring to these files, I noted that
  "GPL-license.txt" is also used in the files below:
    - release/windows/installer/00.sconsblender.nsi
    - release/windows/specific.sh
  but these files should't be affected by this commit, but please check :)