RTS: Allow to put subtitles higher than video frame with override
placement and subtitles placed relative to video frame.
Increase limit on subtitles override placement feature.

Fixes #2834
Use the existent macros to check for handles.
CID 1224581.
CID 1224582.
CONTRIBUTING.md: remove OpenID info.

We don't use it anymore.
Remove unneeded check.
Run astyle.