Support for transparency in icons about memcardrex

[ShendoXT]

Some BIOSes have different interfaces. There are ones with black background color
where this transparency doesn't matter much.
More info here, http://www.emutalk.net/threads/15115-PSOne-BIOS-SCPH101-Shots

As for transparency issue, I hope this will sufice.

[DeadlySystem]

Thanks for caring! While it does fix the issue with Spyro, I don't think it's a correct solution. It probably makes things worse in many other cases. As I said in the report, I think a color is only transparent if the palette entry is all-0, i.e. in the loop check if saveData[slotNumber, byteCount + 96] == 0 && saveData[slotNumber, byteCount + 97] == 0, and only then set THAT color to Color.Transparent. Ideally, you could draw an icon with first palette color = black and check if it's really black in the BIOS I'm showing above, I think it's SCPH1001 (BTW, this is an NTSC BIOS. The PAL BIOS has the black background. The guy from Nocash is German, so he probably tested with a PAL BIOS). But I think it will appear all-black, not completely transparent. Also, I'm not sure about the mapping of colors from the editor. You can't draw in transparent right now. But that's a more complex issue and probably less relevant. I'm just worried about preserving the original colors.

[ShendoXT]

Thanks for the heads up, It should work properly for all icons now.

Also, as PS1 BIOS backgrounds aren't consistent i added option to change it in the
preferences dialog.

I also added you to the "Thanks to" list in the application for the suggestion :).