Allow MP3 detection to tolerate blank frames.
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.
Merge pull request #61 from Gaerzi/master

Sync with my fork.