There is now a bm_get_color_i() function in the Bitmap API.
There are two new options on the Editor's Tileset menu: "Reload Image" and "Properties"

"Reload Image" just reloads the tileset bitmap; useful if you've got the bitmap open in a paint program.

The "Properties" option pops up a dialog that allows you to change the border of tiles on the tileset bitmap and the mask color on the bitmap.

The Properties dialog required that I change the file format and the internal representation of the tilesets a little bit.
The map now takes the tileset border into account when drawing the map
Fixed an issue with selecting tiles with borders on the tile canvas
I now support Ogg Vorbis music through a Music() function and a MusicObj object and related methods in the Lua script.
The music objects are also read from PAK files and managed in a resource cache in the same way as Wav objects.

Actually, you can use any music type supported by Mix_LoadMUS() (https://www.libsdl.org/projects/SDL_mixer/docs/SDL_mixer_55.html#SEC55) if you're willing to build the other libraries yourself.
The "Tile Border Input" in the tileset properties dialog is now a spinner instead of a value input.