Shrimp Shader Generator FLTK2 GUI (SVN)

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.

- Add Copy and Paste of group
- Copy of connections between block as well
- Delete of group
- Offset the position of copy blocks
- Add cut of block (paste of cuted blocks not working now)

Updated examples to use the updated environment block.

Added block to show the micropolygon grid. Changed default type of input normal to Complex Fresnel block, from vector to normal type. Changed environment block parameters, and the resulting output, which was aov_reflection - should be the block's $(value). Added LDR image expansion to environment block. Changed SHADEOP_PARAMETERS to environment block and tweaked some details. Fixed typos in LDR expansion function in texture header, and added float version of LDR expansion.
Added NDC projection to available projections in texture header. Minor tweaks in helpers header.

The clamped_texture function (4 pairs of texture coordinates), was using tt instead of tt2 in the 1st pair. This is fixed to tt2 as it should be, for both float and color clamped_texture. There was a problem in the "box" projection when getting filterwidth of ST coordinates - filterwidth uses Du() and Dv(), and was being called inside varying conditionals. This was fixed, the filterwidth(ss) and (tt) statements are moved outside the varying conditional. Minor cleanups in texture functions.