Fixed loading dragged and dropped movies.
Added FPS info to file list.
Improved version control

subconvert_version.sh script checks for Subconvert version in the following order:
1) .tarball-version file contents (only generated for dist tarballs)
2) git describe
3) fallback version (currently 1.x-unknown)

Additionaly, it is invoked every time make is called and version.py __version__ variable is changed
with sed (unfortunate hack). It means that version.py will not take into account @PACKAGE_VERSION@
variable.
Removed generated "*.py" files from gitignore.