Playscii 0.9.13

• Added @lunlumo_art's "osamu-micro" character set to built-in charsets library.
• Game Mode: SpriteRenderables should remember their source image's filename just in case it's useful later.
• Game Mode: tiny fix for player blob shadow z order in maze example game.
• Updated dependencies and Python version (now 3.7.5) for Windows and macOS builds.

Fixes for the following issues reported by Ebyan Alvarez-Buylla, thanks!

• Backspace key now functions same as Delete key (clear document / selection) in Art Mode.
• On macOS, treat Command key as interchangeable with Control key.
• Fixed resizing art not setting its "unsaved changes" flag.
• Replaced a few references to "Mac OSX" in documentation with "macOS".
• Fixed Grab tool setting a new selected xform not updating the picker popup.
• Rotate tool should now update cursor preview immediately after a paint.
• Fix a crash using Grab tool when Art Mode has no art loaded.
• Added "Flip affects xforms" setting to Art menu, now enabled by default. Flipping horizontally or vertically changes character transforms as well, producing the expected flip result. Turning the setting off produces the old behavior.
  • Add two new character transforms, didn't know what to call them exactly: "Flipped 90" and "Flipped 270", for handling horizontal and vertical flips of rotated (90 and 270 degrees) characters.
• Fixed crash when using Rotate tool on flipped characters.