Merge pull request #2 from Benglin/master

Implemented shaders for billboard text
Merge pull request #3 from Benglin/master

Added "vViewport" variable to "BillboardTextModel3D"
Merge pull request #4 from Benglin/master

Added texture support for "BillboardTextModel3D"
Update shader name. Init collections.
Merge branch 'master' of https://github.com/DynamoDS/helix-toolkit into ianMaster

Conflicts:
	Source/HelixToolkit.Wpf.SharpDX/Resources/_default.bfx