Patch release FBX2glTF v0.9.2

The second patch release of FBX2glTF continues our march towards the 1.0 feature set, while fixing some bugs that've cropped up.

The next major TODO item after this is Stingray PBS support.

New features and improvements:

• Support for FBX Blend Shapes, including progressive morphs: #33.
• For vertex-coloured surfaces, we now splice off all transparent triangles (defined as containing at least one non-opaque vertex) into their own separate glTF level mesh primitive: #32

Fixes

• Enabling Draco support no longer results in an immediate program crash.
• Cope gracefully with polygons that explicitly opt out of any material.
• Empty animations no longer result in the generation of a spec-violating empty array. Thanks @robertlong!
• Texture resolution now works properly when converting a .fbx in our current working directory.
• The --keep-attribute option was inadvertently disabled. It's now back online.
• The NPM module now reports error feedback correctly.