Shrimp Shader Generator FLTK2 GUI (SVN)

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.

NEW: added the 'array' type, not yet functional

ENH: Escape key doesn't close Shrimp anymore

-Add copy/paste of blocks: second pass after paste the selection is toggle on the new pasted block you can move them by click and drag on one of them.

-Add copy/paste of blocks: first pass(need to do copy/paste for group and tweak paste location for visiblity ,right now the paste is at the same location of the original copy)