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