Subconvert

* ADD: SubConvert updater
* ADD: encoding detecting (optional)

* FIX: unhandled assertion errors which were caused by incorrect subtitles

* ADD: setup.py (installer)
* ADD: GUI
* ADD: option to stop converting when file exists. Not only it stops file from
being updated but also quits batch work.
* FIX: remove file extension from subviewer's [TITLE]
* FIX: let the shell find python in $PATH
* FIX: Add maximum file size limit to subtitle files.
* FIX: Better parsing state output.
* FIX: Don't save not completely parsed files anymore.

* ADD: TMP sub formatting
* ADD: SubViewer sub formatting
* ADD: full converting subtitles without sub end time
* ADD: support subtitles with header
* FIX: error on -m option mistyped
* FIX: error that prevented sub parsing when no sub end time was present

* ADD: mplayer auto-check more movie formats: mkv, mpg, mp4 and wmv
* ADD: handle multiple input files
* ADD: option to specify output file(s) extension
* FIX: SubRip incorrect parsing (trivia: in my test subtitles a word which
starts with 'f' appears for the first time in 119th subtitle)
* FIX: not clear notifications about parsing and IO operations state + add some
more info to verbose output

* FIX: Uniform backup system
* FIX: A lot of code refactoring. Now works slightly faster