#2 srttool option to strip tags

[Jean Delvare]

I would like srttool to be added an option to strip tags (parts of subtitle text which is inside curly braces in .srt files.) Not all players handle such tags, so it can be convenient to remove them.

Another useful, related feature would be an option to strip only positional tags ({\pos(x,y)}). Authors sometimes include such tags to prevent subtitles from colliding with other text, but for users like me with a legacy 4:3 screen, it's actually more convenient to leave all subtitles in the lower black stripe all the time.