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.

Further work on Pica emulation

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- The methods "InsertBeforeX/Y/Z" and "Append" have been replaced by more versions of MakeVec, which now also supports building new vectors from vectors.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.

Fix threading for Qt5.

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.

Remove documentation for external modules.

We don't need these and they clutter up the repository.

Added FS functions to Archive and Archive_RomFS

Removed unused citra.h

Common: Add a clamp function to math_utils.h

ARM: Remove a forgotten const in vfp.

Revert "Removed redundant loop in EmuThread::run()"

Use Qt5 by default for citra-qt project.

Core: Use std::array for managing kernel object space

Common: Get rid of an unnecessary forward declaration in symbols.h