Shader: Implement EX2 and LG2 in interpreter/JIT

Add coding style about includes

videocore: Added RG8 texture support

Update boost external to v1.59.0

Fix Linux GCC 4.9 build (complaining about undeclared memset)

citra-qt: Improve pica command list widget (add mask, fix some issues)

Shader debugger improvements

Renamed "Iteration index" to the (hopefully) more intuitive "Cycle Index".
Added flexible space at the bottom of the widget.

Introduce a shader tracer to allow inspection of input/output values for each processed instruction.

Now supports dumping the current shader and recognizes a larger number of output semantics.

Handle `FileType::CIA` in `switch` statements

citra-qt: save path for recent files loaded

vfp: use std::swap where applicable

Handle invalid `Log::Class`

Vertex Shader JIT for X86-64

- Config: Add an option for selecting to use shader JIT or interpreter.
- Qt: Add a menu option for enabling/disabling the shader JIT.

- Also renames "vertex_shader.*" to "shader_interpreter.*"