#24 .SRx file: Provide a way to select the palette to be used, when possible

[SD Snatcher]

The importance of the Graph Saurus multi-palette support:

Graph Saurus PLx files support up to 8 palette sets for the same image. This was used in many images, with interesting results. But nowadays, RECOIL renders the SRx and GLx images only with the 1st palette contained in the PLx file. If possible, please think of some way to display all the entries of the palette, be it interactive or not.

The lack of multi-palette support causes the users to miss important features. I attached here a selection of examples:

• DS07BGV: This image features 3 palettes, so you can select a specific moment from twilight to night. Without multi-palette support, users can only access the twilight version of the image
• GSR1DATA: This image has a hidden creature in the window. It's only shown when the palette set progresses. Without multi-palette support, users will never know that the creature is even there.
• GSR1DATA: This is the simpler image of this set. But it's nice to see how this image is affected with different colors.