Update AssimpJSONLoader.js

sometimes assimp2json does not add texturecoords
Minor improvements.
Merge remote-tracking branch 'origin/dev' into dev
Fixed SceneLoader not loading Textures properly. Fixes #4908.
Update WebGLRenderer.js

var c4 is not being used.
Merge remote-tracking branch 'astrolabio/patch-1' into dev
Rescued webgl_loader_scene example.
Simplified SceneLoader example.
Fixed Animation relying on object.position = vector pattern. See #4924.
Simplified misc_animation_keys example.
Still doesn't work though...
Updated builds.
STLLoader: Using statusText instead of responseText on error. See #4913.
Merge remote-tracking branch 'anasAsh/patch-2' into dev