Adding detection of a "hifi" global light in a FBX file used to pass information

-extract light information from the FBX file (but doesn't use it for rendering)
- if a light node is called "hifi_global" then the light intensity is used to control the intensity of the light maps
- if value is 0 then this kills the light map effect

- if not present, the lightmaps are applied normally from the ambient texture