Shrimp Shader Generator FLTK2 GUI (SVN)

Fixed another problem in shader invocation for prman.

Fixed potential shader compiler invocation problem with prman.

Updated the Lafortune block for 2 coefficients.

Added Mario Marengo's complementary/error function, and removed the C shadeop. Added the Schlick anisotropic specular term, and updated the remaining BRDF blocks.

Updated typo in distributions. Complementary error function will be replaced later.

Updated the Trowbridge-Reitz distribution. There is a normalization term (we'll have to use a constant for the time being, until i gather more info on this - the paper is hard to find).

Updated distributions header to fix a typo in trowbridge-reitz PDF.

Added the Strauss empirical BRDF to the local illumination models header, as well as the respective xml block.

Added the Banks fast anisotropic shading model block.

Added the Banks fast anisotropic shading model in the shading models header, and the respective block.