Sprite mode and lock colors for all backbuffers for animations

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To avoid problems where an sprite animation ends up having different color 
palette for the different animation steps in multicolors and sprite colors, I 
would like a feater that goes through all the backbuffers and locks the colors 
to a specific palette when setting up a "New" project.

Of course, I need to be able to change the colors on free will after, but 
initially, all buffers in sprite mode should contain the same palette setup as 
from buffer nr 1.

Original issue reported on code.google.com by magnar...@gmail.com on 14 Jan 2014 at 6:30