C++-ized Template specializations

• Switched CGTextureMapping.c over to CGTextureMapping.cpp in order to use C++ templates.
	• Appropriate `__cplusplus` conditionals and `extern "C"` blocks in CGTextureMapping.h.
• `createDestImageData()` given two template arguments: `OutsideOfQuadUVMode tUVMode` and `int tComponentCount`.
	• Also offers a plain-C createDestImageData() which uses switch/cases internally to call the appropriate template.
	• `kComponentCount` constant and `DestImageGenInfo#uvMode` removed in favor of template arguments.
• `genDestImagePixelBytes()` likewise templatized on `tUVMode` and `tComponentCount`.
	• New `normalizedTexelXY<OutsideOfQuadMode tUVMode>` handles the wrapping logic with a specialization for each mode.
	• New `copyBytesToPixelFromTexel<int tComponentCount>` handles copying each component's bytes with specializations for 1, 2, 3, and 4 components.