Fixes to Game startup when using a unit test runner.
The Content.RootDirectory cannot be absolute.
Removed local directory reference.
Using AppDomain.CurrentDomain.BaseDirectory seems to be a more reliable way of getting the working dir.
I was wrong.... Content.RootDirectory can have an absolute path.  MonoGame needs fixing here.
Game takes care of disposing GraphicsDeviceManager.
Removed old shader files.
Fixed shader format to write the shader code length as 32bit integer.
Incremented MGFX version to 5.
Rebuilt stock effects to MGFX version 5.
Fixed SamplerStateCollection to reset to SamplerState.LinearWrap.
Sharing the sampler initialization with Clear().
Fixed bug where EffectParameter data was shared among cloned effects.
Removed EffectPass.Initialize() which was unused and not XNA.
Merge pull request #1541 from SickheadGames/samplerfix

Fixed SamplerStateCollection to reset to SamplerState.LinearWrap
Merge pull request #1531 from SickheadGames/mgfx

MGFX Large Shader Fix
Merge pull request #1542 from SickheadGames/effectfix

Fixed EffectParameter Bug
Fix for delete BufferRender.  Should only be GLES and not OpenGL.
Merge pull request #1545 from kjpou1/develop

Fix for delete BufferRender.  Should only be GLES and not OpenGL.
Fixed the Matrix.CreateBillboard function so that both overloads work.
Switched overloads for efficiency.