Shrimp Shader Generator FLTK2 GUI (SVN)

Added complex arithmetic blocks and complex Fresnel block (unpolarized light), using functions defined in odwikicomplex.h header, from the Odforce.net Odwiki, and the Odwiki BRDF article, by the Odforce community and Mario Marengo. Added respective header, odwikicomplex.h, updated shrimp_helpers.h for hyperbolic sine, cosine, tangent, instead of being defined in the their respective blocks bodies. Updated the trace() block for a typo and incorrect macro definitions and checks. Many thanks to once again, Mario Marengo, Jason, and the Odforce and Odwiki community.

Changed current shaders' XML code tag from 'code' to 'rsl_code' to easily support other kinds of renderers in the future

Updated symbols definitions, so that we don't redefine macros (and have the subsequent warnings/errors).

Updated coordinate conversion blocks with add type_parent and defaults.

Added a note about the INIT_AOV_PARAMETERS macro in shadingmodels. Removed topolar2d() from shrimp_helpers, and created an header for coordinates conversions, as well as its respective blocks. Updated the Voronoi (Karlsruhe/Moscow metric) diagram block to use the new coordinate conversion. Updated the rt_environment scene (it was using some xml from older blocks).

Moritz Moeller reported shrimp.cpp was missing memory include, for std::auto_ptr. Fixed this.

Added a fix for the raytraced glass functions, so that Pixie could ignore some portions.

Added support for preset AOVs.

Bug: default preferences.xml file didn't include the renderer code

Fixed problem in the Trowbridge-Reitz distribution, using the description from Pat Hanrahan's 1995 course handout.