videorec: Fix flushing encoders
When passing NULL frames, encoders empty their queues, but we have
to stop polling from them when they don't any more data.
1. Fix broken trainings/missions
2. Update translations (check fireforge for patches)
3. Check copyright headers
4. Changelog
5. Turn debug stuff off (frontend console output)
6. Update message in game server, update check for client version
7. Make a branch
8. Make packages
9. Test packages
10. Upload (hedgewars.org, fireforge.net, gna.org (rsync --delete -avr --rsh="ssh" . unc0rr@download.gna.org:/upload/hedgewars))
11. Post news (hedgewars.org, hedgewars forum, fireforge.net, gna.org, happypenguin, etc.)
12. Make tag (svn copy svn+ssh://unc0rr@svn.fireforge.net/svnroot/hedgewars/branches/0.9.7 svn+ssh://unc0rr@svn.fireforge.net/svnroot/hedgewars/tags/0.9.7 -m "Tag for 0.9.7 release")