Add BroadcastInt function to helpers.
Separate dithering functions into their own file.

Also optimize the dithering a little bit using a LUT.
Remove rdp_pipeline_crashed from non-debug build.
Remove unused popmessage function.
Pull more out of core file.
Remove unused vi_integer_sqrt function.
Start splitting framebuffer access functions.
Cleanup recently split framebuffer reads.
Move framebuffer writes around.