Added missing IsDisposed properties to SoundBank and WaveBank.
Merge pull request #2951 from SickheadGames/develop

Added missing IsDisposed properties to SoundBank and WaveBank.
Hooked up Cue.Apply3D().
Merge pull request #2952 from SickheadGames/xact1

Implemented Cue.Apply3D()
Removed slow and incorrect DateTime.Now.
Fixed ReleaseAllTouches() to use CurrentTimestamp.
Fixed all other uses of DateTime.Now in runtime to use fast and garbage free DateTime.UtcNow.
Merge pull request #2953 from SickheadGames/touchfix

Remove DateTime.Now
Merge back from develop
PerformanceCounter is not an XNA4 feature.
Remove redundant glPixelStore calls