Brave New World

Changelog:

• complete redesign of GUI which has a lot of cool features:
  • subtitle editing
  • undo/redo
  • batch or single file works
  • reencoding of subtitle file
  • side panel
• introduced Subtitle Property Files
• introduced output file syntax ("%f" substitution)
• correct internationalization (moved *.po files + use of ngettext)
• HUGE code refactoring
• changed hand made install script to autotools
• migrate Subconvert to Python 3
• subconvert by default spawns GUI. Use '-c' to access commandline interface