DX9 style HLSL in, GLSL / GLSL ES out.

A continued development from ATI's HLSL2GLSL. I'm changing it to make it work for Unity's use cases; might totally not work for yours!

For an opposite tool (GLSL ES to HLSL translator), look at Google's ANGLE.

• Made it build with VS2008 on Windows and XCode 3.2 on Mac. Build as static library.
• Feature to produce OpenGL ES-like precision specifiers (fixed/half/float -> lowp/mediump/highp)
• Fixes to ternary vector selection (float4 ? float4 : float4)
• Fixes to bool->float promotion in arithmetic ops
• Fixes to matrix constructors & indexing (GLSL is transposed in regards to HLSL)
• Support clip()
• Support Cg-like samplerRECT, texRECT, texRECTproj
• Support VPOS and VFACE semantics
• Fix various crashes & infinite loops, mostly on shaders with errors
• Cleaner and more deterministic generated GLSL output
• Unit testing suite
• Simplified interface, code cleanup, unused code removal, merge copy-n-pasted code, simplify implementation etc.
• Added support for emission of const initializers (including struct and array initializers using GLSL 1.20 array syntax).
• Removed all constant folding functionality as it was completely broken.
• A myriad of smaller bug fixes.
• Support DX10 SV_VertexID, SV_PrimitiveID and SV_InstanceID semantics.
• Support for shadow sampler types (samplerRECTShadow/sampler2DShadow etc.) which generate appropriate shadow2DRect/shadow2D etc. calls.
• Fixed unaligned swizzled matrix access & assignments (view._m01_m02_m33 = value)

• Only Direct3D 9 style HLSL is supported. No Direct3D 10/11 "template like" syntax, no geometry/tesselation/compute shaders, no abstract interfaces.
• I bumped into some issues of HLSL2GLSL's preprocessor that I am not fixing. Most issues were with token pasting operator. So I preprocess source using mojoshader's preprocessor. Grab latest from mojoshader hg, it's awesome!
• On Windows, the library is built with _HAS_ITERATOR_DEBUGGING=0,_SECURE_SCL=0 defines, which affect MSVC's STL behavior. If this does not match defines in your application, totally strange things can start to happen!
• The library is not currently thread-safe.

Used in Unity and bitsquid engine, and seems to work quite ok.

Support for DX11 features will probably not be added due to the bad condition the original code is in (very obscure and inefficient), instead maybe a new cross-compiler will be made.

No optimizations are performed on the generated GLSL, so it is expected that your platform will have a decent GLSL compiler. Or, use GLSL Optimizer, at Unity we use it to optimize shaders produced by HLSL2GLSL; gives a substantial performance boost on mobile platforms.