A regression from 7f61a09478. The current frame is the currently
displayed frame, not the frame that should be displayed next. Thanks to
clone2727 and Marisa-Chan for the explanation and fixes
This is the first part of the changes to make the engine use RGB555
internally again. This is done to simplify the rendering pipeline -
the engine will use RGB555 internally, but will output to RGB565.
The overall changes have been broken into two commits, thus this
first commit will break all the game colors
Filippos Karapetis