Define texture level mode
Set texture bias in constant mode
Merge pull request #5905 from raven02/patch-9

Define texture level mode and set bias in constant mode
Use getMpegVersion to get ctx->mpegVersion
Temporarily (?) revert ffdba45b4bbd because of massive perf drop in GT, working around #5900

Not sure what to do about the Chinese Tactics Ogre though...
Missing default case :(
Merge pull request #5906 from raven02/patch-10

Use getMpegVersion to get ctx->mpegVersion