Removed unused non-XNA method Effect.End().
Made the Effect collection classes immutable.
Changed all Effect classes to use arrays to save memory over List<>.
Added EffectParameterCollection.Empty and EffectAnnotationCollection.Empty which saves alot of memory.
Check in of Single solution projects - from develop branch onlu, no changes reqd

* vs solution - MonoGame.Framework.sln - Manages all windows based solutons

* Xmarin solution - MonoGame.Framework.Xamarin.sln - Manages all solutions supported by Xamaring Studio (Needs Trial or Ent license to build)
Mipmap generation for DXT textures.
Mipmap generation for PVRTC compressed textures.
Fixed crash when changing the value of a processor parameter.
Fixed Dll lookup in MGCB to look in executable path.
Merge branch 'develop' into develop.singlesolution
Merge pull request #1639 from DDReaper/develop.singlesolution

Check in of Single solution projects
Merge pull request #1645 from SickheadGames/GenerateMipmaps

DXT and PVRTC Mipmap Generation
Merge branch 'develop' into effectopt
Merge pull request #1660 from SickheadGames/effectopt

Effect Memory Optimizations
Merge branch 'develop' into develop.datacontract