v1.0.0-beta.22: Faster loading and internal stuffs

This release contains mainly chore work to the game’s codebase and other minor stuff.

• Faster loading. Bemuse will now download 2 package files simultaneously. This should result in faster package downloads.
• The markdown parser has switched to use markdown-it library.
• The markdown will be parsed like GFM, which means line breaks will create a new line when displayed.
• Changed file names and CSS class names to be consistent with JSX class names across the codebase.
• Allow server query string to be used instead of the more verbose BEMUSE_MUSIC_SERVER.
• The bmson related code has been moved to bmson project, to be incorporated into bemuse-indexer, and subsequently, bemuse-tools, in order to give bmson support to these tools.
• Update isparta relying on a older version of webpack that uses an incompatible regenerator, causing build errors on the CI.