Define converter functions for sets of pixels in the gfx scope. Fixes #676
Merge branch 'master' of https://github.com/andreasgal/j2me.js into optimize_pixel_manip
Use the same parameters format for all the pixel converting functions
Remove contextToRgbData helper function
Remove rgbDataToContext helper function
Fix alignment in ABGRToARGB4444 and ARGB4444ToABGR
Merge pull request #699 from marco-c/optimize_pixel_manip

Optimize pixel conversion functions