Enable "rename each" for texture editor.
Add Blake Stone's colormap dimensions to colormaps.

Also coincidentally fix an old bug. The valid_flat_size array had 16
triplets, but n_valid_flat_sizes was 17...
Support for ROTT colormaps.

Added a function to arbitrarily change an image's dimensions, as long as
it doesn't change the pixel count. This allows the GfxEntryPanel to
display 256x32 colormaps as well as 64x128 flats.