Shrimp Shader Generator FLTK2 GUI (SVN)

Continued tweaking existent blocks so that more meaningful input pad names are used and displayed.

Updated shading functions block to have more meaningful input pad names, small tweaks to the blocks.

All blocks now display their input pad names. Colors tweaked so that input pad names are light blue, hovering orange, together with small UI tweaks that should improve readability. Group names problem fixed, no longer centered, now it's above group widget.

Added aov_opacity AOV to root block source and AOV headers, and Thin Film Interference block (spec6), based on Jens's VEX shader. Tweaked rgb<>spec6 functions for Aqsis workarounds (component access can only be made with (xyz)comp in Aqsis). Both Aqsis and Pixie seem to accept arrays as function arguments, but there are some problems yet with rgb<>spec6 in both Aqsis and Pixie.
Glass block tweaked for Aqsis and Pixie workarounds (component access, array initialization, ternary operator expressions). Added missing vector exponent, maximum, and minimum functions to helpers header.

Added color conversion functions (rgb>spec6>rgb), based on Mario Marengo's VEX functions from his glass shader. Added optics data (Schott catalogue) for glass types, generated by modified mktables.C, also taken from Mario Marengo's glass shader. Changed the glass block so that dispersion in RYGCBV is done optionally if "usespec6" is toggled on, in which case the "ior" variable is ignored in favor of the IOR data taken from the tables, controlled by the "optics" variable (range [0,112]). Tables will get FreeSnell/Sopra n+k data later, color header will get extra color space conversions later as well.

Updated light blocks so that the user can toggle custom lights as nondiffuse/nonspecular. Updated root block source so that light shaders have a default output uniform float __nondiffuse/__nonspecular shader parameter, which the blocks override. Updated the glass shader block and the function, so that it returns both color and transparency - transmission based shadows based on Alan Warren's port of the VEX shader by Mario Marengo.

Small update to glass function, maximum continuation is float.

Only 3delight seems to product correct internal reflections without the need to reverse N if the ray is travelling inside medium, other renderers need reversed N, otherwise fresnel() will go the way of the wouwous.

Added bias for glass's environment().

Typo in vmax/vmin, return type should float, not color.