Rework PIFBoot ROM emulation.

Previous PIFBoot ROM emulation was more complex than needed (and possibly contained errors).
Merge pull request #41 from bsmiles32/pifbootrom_hle

Rework PIFBoot ROM emulation.
add a render callback to the input plugin. for on screen rendering of input plugins
add an option to build against GLES2 instead of OpenGL
Create OpenGL ES2 context when compiled with USE_GLES=1
new_dynarec: Fixed BGTZ/BLEZ

When testing 64bit mips registers, the low 32bit part should be tested
in unsigned mode.
Merge pull request #43 from fayvel/gles2_fixes

Allow to build against OpenGL ES2 with SDL2
Merge pull request #44 from Gillou68310/master

new_dynarec: Fixed BGTZ/BLEZ
bump input api version
add documentation for the RenderCallback input api change
Merge pull request #42 from krnlyng/input

input plugin proposal
dont throw an error message when connecting to older input plugins