Prevent referencing non-existent bones.
Added missing effect content writers.
Emit multiple geoms per mesh instead of multiple meshes.
First pass material->effect processing.
A little more work on the model processor.
Yet more Model Processor progress.
Support for Byte4 vertex elements.
Revert "Prevent referencing non-existent bones."

This reverts commit b240c03860cb741d131ec7e6de83cbc96da20f3d.
Add in the remaining vertex content types.
Support writing effects with no texture defined, which appears to be the case in XNA.
Add a default color channel in (not sure about the constant value), as XNA appears to.
Fix vertex/index buffer sharing within a mesh.
Looks like the color channels come in at the processor level, not the importer.
Value didn't exist yet.
Mimic XNA single mesh simplification case
Removed dead code
Merge pull request #2590 from SickheadGames/ModelPipeline

Model importer and processor improvements