Can you add to support define custom rgba value?

[GoogleCodeExporter]

Really a good tool:)

the default value is this in CompressionOptions::reset():
m.bitcount = 32;
m.bmask = 0x000000FF;
m.gmask = 0x0000FF00;
m.rmask = 0x00FF0000;
m.amask = 0xFF000000;


sometimes I want to define the custom value, for example:
m.bitcount = 16;
m.rmask = 0x00000F00;
m.gmask = 0x000000F0;
m.bmask = 0x0000000F;
m.amask = 0x0000F000;
but there is no param compression options for this
Compression options:
  -fast         Fast compression.
  -nocuda       Do not use cuda compressor.
  -rgb          RGBA format
  -bc1          BC1 format (DXT1)
  -bc1n         BC1 normal map format (DXT1nm)
  -bc1a         BC1 format with binary alpha (DXT1a)
  -bc2          BC2 format (DXT3)
  -bc3          BC3 format (DXT5)
  -bc3n         BC3 normal map format (DXT5nm)
  -bc4          BC4 format (ATI1)
  -bc5          BC5 format (3Dc/ATI2)
There is no way to change the value unless change the code. 
Hope to define params like this "-r00000F00 -b0000000F -g000000F0 -ax0000F000 
-bit16" in the commond line

Original issue reported on code.google.com by dark.z....@gmail.com on 10 Jan 2014 at 9:00