Shrimp Shader Generator FLTK2 GUI (SVN)

FIX: RIB scenes were appended to the list each time the preference dialog was opened

-update usage section with information of the blending mode number for each mode

- New block in a new section call Layering :blend color ,blend two color using the selected blending mode

Added some fixes and comments to the Cook-Torrance model, and the microfacet distributions and shadowing/masking functions in their respective headers.

ENH: experimental array support (without the message passing stuff)

- fix scene menu duplicate entry,appear after access to file/options dialog

-Add number of blocks listed in the doc

FIX: array support level 1 completed

ENH: moved array value declarations to the local variables

FIX: array valued variable replacement now works properly