Also write PNGs with libpng, and BMPs with SDL, and have the renderer only generate a large PNG thumbnail, and disable HTTP/2 multiplexing for now so we don't get banned when loading avatars.
simon pls reply to the stupid emails already.
Also Factor out app constants that mods might change into Meson options and clean up format::URLEncode in the process, convert app and document icon data in arrays to actual images, actualize AppStream data for possible future packaging, add alternative command line format for opening filesystem saves and ptsave URLs, fix a memory leak in Platform::GetCwd, and add format::URLDecode.
Also restructure meson.build and the ghactions workflow a bit, and enable -ffunction-sections and -fdata-sections.
Note that starcatcher uploads have not been tested and most likely don't work.
