Screen contents are now displayed using textured quads. This can be updated to expose an FBO once an OpenGL backend for when Pica rendering is being worked on. That FBO's texture can then be applied to the quads.

Previously, FBO blitting was used in order to display screen contents, which did not work on OS X. The new textured quad approach is less of a compatibility risk.

Pica/Math: Improved the design of the Vec2/Vec3/Vec4 classes and simplified rasterizer code accordingly.

- Swizzlers now return const objects so that things like "first_vec4.xyz() = some_vec3" now will fail to compile (ideally we should support some vector holding references to make this actually work).
- The methods "InsertBeforeX/Y/Z" and "Append" have been replaced by more versions of MakeVec, which now also supports building new vectors from vectors.
- Vector library now follows C++ type promotion rules (hence, the result of Vec2<u8> with another Vec2<u8> is now a Vec2<int>).

Pica/citra-qt: Replace command list view and command list debugging code with something more sophisticated.

Note: There is a pre-existing issue with booting a new game in that it keeps the old EmuThread.
The GL code now supports this but the Core still doesn't.

Connect the emu_thread start/finish to a moveContext slot.

These avoid relying on memset for clearing the arrays.

Changed HLE function return methods to be static inline functions.

Returning a copy of the string is what was likely meant to be done.

Most functions already operate on std::strings. This also removes the need to manually null terminate thread names.

entry_point would not be added to the string. Also used StringFromFormat
so that the buffer is unnecessary.

On POSIX systems mmap will return MAP_FAILED ((void*)-1) instead of a null pointer.