To do:

• reject impossible music
• accept docx files?
• [~] gui input
• pdf output
• allow rests
• allow pedal diagrams mid-music?
• allow multiple sections per file?
• [~] good error handling
• give correct enharmonic spellings
• give correct pedial diagrams when initially unspecified
• insist on a specific pedal (eg so B and Cb can be used for a bisbig.)
• fix early placement bugs
• fold as much as possible into A* search, especially early placement
• [~] fine-tune costs
• prettify pdf output
• early placement cost scales with how early it is
• specify output format
• change input syntax to use [ ... ] for chords
• split Cli into two structs to make help more readable