LightUp v6

LightUp v3.1a

This new version of LightUp has an enhanced graphics engine as well as variety of support for working at higher resolution.

Fixes and Enhancements in this release
- Faster rendering shaders
- Much improved compression of luca file content
- Auto-scaling tooltips for Retina displays
- Higher resolution water shading
- Fixes to CIE sunlight
- Allow embedding https:// URL in luca
- Improved stability for thumbnail raytracer
- better reticle rendering
- Exports Scene Cameras in FBX files
- offsets for LightSamplers to avoid z-fighting
- fixes for face-me component rendering in Still images