* New built-in wallpaper: "Dotted paper (dark)" is a dark-themed wallpaper.
* New built-in palette: "Neon Bright" with bright colors for dark levels.
* New cheat: "warp whistle" to automatically win the level.
* In case the user has a VERY LARGE screen resolution bigger than the full
bounds of a Bounded level, the Play Scene will cap the size and center
the level canvas onto the window. This is preferable to being able to see
beyond the level's boundaries and hitting an invisible wall in-game.
* Make the titlescreen Lazy Scroll work on unbounded levels. It can't bounce
off scroll boundaries but it will reverse course if it reaches the level's
furthest limits.
* Bugfix: characters' white eyes were transparent in-game. Multiple culprits
from the `doodad convert` tool defaulting the chroma key to white, to the
SDL2 textures considering white to be transparent. For the latter, the game
offsets the color by -1 blue.
