Shrimp Shader Generator FLTK2 GUI (SVN)

PRMan doesn't accepts Ol global variable (light opacity). Add workaround so that generated light shaders don't output Ol.

Fixed typo in Stanford Buddha container scene (Attribute).
Fixed missing control points in spline() in the lichen example scene.

Fixed camera position in Stanford Dragon container RIB.

Fixed remaining RIB scenes. Added updated Stanford Dragon scene.

Added Clipping to the Shrimp generated RIB, and fixed Quantization. Added archives/ directory with preview objects (read in main scene via ReadArchive). Tweaked main "container" scenes. RIB archives (Stanford Dragon, Stanford Buddha, Stanford Bunny, and background box) by Uros Simic.

Cleaned up the RIB generation, added some extra options, such as searchpath defaults, and other RI statements. Prepared for the cleaned up RIBs.

Changed shTile x/y frequency to uniform storage in xml block (as in shapes header). Updated bakeptc example (forgo tto disable rasterorient dicing), and added DisplayChannel "float occlusion" to the bakeptc example's RIB root block. Fixed ternary operator expression in glass model when choosing between glossy or specularbrdf().

Fix point/vector casting in helpers header (rotate(), :754). Changed default display on 3delight. Removed -lintlt on PRMan shader compiler default command, and added framebuffer to list of PRMan displays. Changed Ashikhmin-Shirley diffuse block's default values. Removed light categories from Kubelka-Munk block (no illuminance, meant for "sandwich models"). Updated bronze example scene, Spline_2 block was using "hermite" basis and missing a control point.

Changed Ward isotropic normal input from "vector" to "normal" type. Changed default eta on Fresnel block from 1.5 to relative index of refraction (to the air ior of 1.0), so eta defaults to 0.75, good default for dielectric surfaces.
Added thin film interference example network (uses 'uffizi-large.tdl' environment map, from Paul Debevec's HDR gallery, http://www.debevec.org ).

Added envspace variable to Ashikhmin-Shirley block, and its environment sampling function.