some skin updates

[DieGo367]

Bowser's Fury and Lake Lapcat v1.0.2

• Converted music to WAV.
• Both BGMs now use a startup jingle.
  • Previously, the tracks were doubled to hide the bad loop at least once, but now they can be half as long and loop properly.
• BGM and sounds are louder, should be closer to the standard DSi Theme in volume than before.
• Added DS mode variants of the custom fonts.

  Minecraft v2.1.2

• Converted old GRF images to PNG/BMP.
• Converted music to WAV, using a slightly higher frequency.
• Added DS mode variant of the large font (the small one was already present).
• Description updated to credit the original render artist Mursztin and music by C418.

  Relaxing Space v1.1.2

• Converted old GRF images to PNG/BMP.
• Converted music to WAV, using double the frequency.
• Minor tweak to the corners of the Start border.

Also updated all screenshots of these themes. They no longer show boxart, and there are now screenshots for Macro mode in each theme.