Do not generate any networking projects for Angle. Angle is just for testing GLES and does not need networking.

Fixes #2592
Merge pull request #2603 from danzel/no-angle-net

Do not generate any networking projects for Angle.
Added custom IEqualityComparer to SpriteFont glyph dictionary.
Replaced internal _texture access.
Removed _characters in favor of auto-property.
Simplified logic around missing glyphs.
Removed always true if statement.
Merge pull request #2604 from SickheadGames/fonts

SpriteFont Optimizations Pt. 1
Don't stop the Stopwatch until we are ready to start the run loop. Previously we'd be accumulating update time while the game loaded, which would lead to _maxElapsedTime worth of updates before the first draw call was made.
Redo the IsRunningSlowly calculation to use a method that closer resembles XNA behaviour. We now count how many lost frames we've had and use that as the trigger.

Fixes #2595
Merge pull request #2607 from danzel/isrunningslowly

Redo the IsRunningSlowly calculation
Merge pull request #2606 from danzel/gamestart-update-spam

Fix burst of Game.Update calls at the start of the game
flibit regrets not doing his homework on XACT back in October
I hate this timer and its entire family
Fix redundant Stop on delayed Instance
Merge back from develop
Implementing the Song.FromURI method with local file support. It doesn't support the remote song playback that XNA4 has, but at least it supports local files without relying on the MonoGame specific ContentManager.Load<Song> fallback behavior.
Merge pull request #226 from brushfiregames/brushfiregames/song-fromuri

Implementing the Song.FromURI method with local file support
When running in debug mode, there are a lot of GL errors printing to the console regarding redundant state changes in glBindFramebuffer. I've added some managed caching of the two framebuffer components and made helpers that make sure we're doing the right thing.
Merge pull request #227 from brushfiregames/brushfiregames/fix-redundant-framebuffer-warnings

Fixing OpenGL warnings about redundant state in glBindFramebuffer