FBX support almost finished

Migrating away from md5mesh to FBX, since that's the standard as far as content folks are concerned.  Loaded up some models from the Unity 3d asset store, so I can compare lighting!  Just had to hook up the textures in my JSON based materials.  It really shows how much I need to implement IBL and reflection comparing output.  I've been thinking about copying the Witcher 3 idea of a simple low-resolution cubemap camera that is indoor/outdoor aware for a fully dynamic probe as all my stuff is randomly generated you can't bake it unless you save seeds.

Working on procedural animation and an all new animation state system currently, so no pretty lighting for a while.  Just using a simple 'skylight' hack in the meantime.  BTW the FbxSdk for Linux works pretty well, which is nice as I didn't have to make a reverse engineered importer just for this.

Note all these are using faked IBL without AO and no shadows to see the difference better.  I'm not saying the implementations are 100% either.  :D

Here's what it looks like with a Beckman Specular BRDF, and minor GBuffer shader tweaks -- similar to the Order 1886:

Burley aka "Disney" -- similar to UE4:

"Kagura Default" which is a GGX + Normalized Oren-Nayar -- similar to Deep-Down reveal:

Beckman + Oren-Nayar vs GGX + Oren-Nayar with paused camera ( for use with photoshop )