Merge pull request #1 from stepmania/master

Update
Preserves backwards compatibility with 10.6

sync_volume_np was introduced in the 10.8 SDK. This commit ensures that
some related constants are defined before calling the function. If they
are not, we fallback to the older logic.
Added functions to ActorUtil for converting the extension to a file type and changed various places that had lists of extensions to use ActorUtil instead of duplicating the list of extensions.  Added webm and wmv to list of video types.
Added MinTNSToHideNotes preference.
Added mod for MinTNSToHideNote so it can be set per-player.
Updated changelog and docs for new mod.
Use operator overloading best practices.

Not all files covered.

Refer to StackOverflow for details: http://stackoverflow.com/a/4421719
Merge pull request #358 from jberney/master

Band-aid fix for Mac OS X fullscreen issues (only when compiled with 10.6 SDK)
Fixed DeltaSeconds actor in timed courses to check whether the pref for the delta exists.
Merge branch 'wolf-operator-best-practices' of https://github.com/wolfman2000/stepmania
Merge pull request #380 from kyzentun/pref_hide_note

Preference and mod for hiding notes that are hit
Merge pull request #366 from kyzentun/bgm_formats

Unduplicate file extension lists.
Use lua_rawget instead of lua_gettable in ActorFrame::IdenticalChildrenIndexLayer to avoid self recursion on invalid number indices.
Forgot to init MinTNTS mod to the value of the pref.
Changed TimingData GetReturnsNumbers metric to optional boolean arg to the functions.