Added %format and %ext(ension), modified %quality and improvements

- Added %format (ex: MP4, WebM, M4A)
- %quality now gives only quality (360p, 128kbps, 4K (no audio))
- Added %ext to allow removal of filename extension.
- Added corresponding placeholders for new additions in language files
- Fixed "user" being used instead of "author"
- If no extension can be found, no extension will be given, letting Chrome deal with it
- Re-added fallback for variables
- Extension/format/quality switch() done better. Custom indentation may not survive to a linter