Switch to integer implementation
ROOL authored
Detail:
  The dynamic range of the values being computed easily fit within integer types, so use these instead of doubles. This makes ScrModes independent of its position in intialisation with respect to FPEmulator once more, and saves 1k of code space too.
  Functions generate_mode_using_gtf(), generate_mode_using_cvt_rb(), generate_cvt3_timing() affected.
Admin:
  Test added to brute force compare float and fixed point results.
  Submission for the EDID bounty.

Version 0.55. Tagged as 'ScrModes-0_55'
862ea508