* Param refactor
collected all the code that reached inside Param (InitCond, Per*Eqn, Expr, Parser) to read/write and stuffed it all back into Param.cpp
made Param extend Expr to avoid any perf penalty (I actually think eval() is a tiny bit faster now)
* presets/tests
* ALWAYS_MATRIX is used with PER_POINT
* use SSE2 to impove initialize_PerPixelMeshes() performance
* TestRunner
very, very simple test framework, but it's better than no framework
(consider investigating adopting something)
* ProgramExpr
