Add 16bit dithering for 256/16M rgb console + fixes

Add scr.rgbcolor to disable 16bit ansi escapes
Disabled by default on windows
Implement ansi to rgb and rgb to ansi conversors
Implement 256 color to rgb bruteforcer
ec: renamed to ecr
Fixes for the VE menu
Drop --enable-devel flag from r2-bindings/README