1.2.1: widescreen menus fill the screen

Widescreen menus fill the screen. Every menu, background and menu effect now reaches the edges of a 16:9 (or wider) screen on its own, by general rules instead of a few hand-made screen layouts:

• Bars, bands, panels and background layers that reach the side of the old 4:3 picture now run on to the edge of the screen (the highlight behind the selected button, the Z: Game Settings bar, the course select frame, the results rows).
• Art the game draws just past the 4:3 edge is shown instead of being cut off.
• Things the game keeps parked off-screen (Player Entry's panels for players who haven't joined) stay hidden.
• The Nintendo/HAL logo screen fills the width; the intro and How to Play movies stay 4:3.
• Fixed: menu descriptions were split in two with a gap in the middle.

Download: unzip KirbyAirRideRecompiled-1.2.1-windows-x64.zip, run kirbyairride.exe and choose your Kirby Air Ride (USA) disc image. Coming from 1.2.0, the game is built from your disc once more on first start (a few minutes). Nothing of the game is in the download. Details: docs/SETUP.md.

8 players online: Kirby Air Ride (8 players).bat. Dedicated server (unchanged): server-1.1.0.