BSplayer 2.5.7.1048

# ADDED
- new osd mode
- option to set subtitles off by default, subtitles are still loaded but not shown
- option to ignore SSA styles
- option to set background color for full screen mode
- support for some Windows 7 features

# FIXED
- unicode file names were in some cases displayed with short name
- fixed wrong language checking with online subtitles
- with online subtitles only default language will now be requested
- fixed always on top bug when returning from full screen mode when sepearate taskbar buttons were enabled
- text inside {} in SSA subtitles will now be ignored
- changed/fixed mkv default audio stream handling
- all online subtitle providers will now be checked at the same time in separate threads