Merge tag 'v0.31.0' into debian

Alpha 31 release
Undo American -> Britsh changes for now.

This will be done all through out the project at a later date.
For some reason, this fixes mantis corpse

All other alien models seem to look correct with this change too. The animation system is reporting the correct frame numbers,
and removing the last frame doesn't seem to help...
Make update-version-number.sh update menu file versions too
Version bump
Merge branch 'vertexpack'
Update changelog.
Merge branch 'master' into debian
Update changelog.
Work around '#directive in the middle of a shader' error on Mesa
Merge branch 'master' into debian
Increase particle system limits.
Add cg_spawnEffects to disable spawn colorgrading since OSX doesn't like it
Fix error message
Move build timer under momentum bar
Fixes #455
Revert "Add a check to avoid sending sync messages while handling async messages"

This reverts commit 1ca7b09bc22b95920768d9b946043a6d8e70aa90.
Causes crash if any player disconnects
Clear the tutorial text when the cvar is disabled
Fixes #457
Restore previous weapon HUD upon vid_restart
Adding /playSound /playMusic /stopMusic command
Merge pull request #463 from mwestphal/master

Adding /playSound /playMusic /stopMusic command