Add proper Don/Ka types to clusters of notes

[vivaria]

This should match most fumens. Some exceptional cases I've seen:

• [x] ~In official fumens, even-numbered clusters of 4 notes will sometimes be ドドドド or カカカカ. Right now, my converter will always use ドドドドン or カカカカッ, since I don't really understand the rules behind it.~ Fixed: Now, all 16th notes and above in groups of 4 will no longer use the don/kat ending character.
• [X] ~In official fumens, sometimes isolated notes will be grouped together, but sometimes they will be treated as single clusters of 1. Right now, my converter will always try to cluster isolated notes.~ Fixed: Only 4th/8th/16th/etc. notes will be clustered. Whole/half notes will not be clustered.
• [x] ~Right now, my logic always treats big notes as their own cluster. But, sometimes you get a cluster like ddddD, and right now my converter treats this as (ドドドドン) + big DON instead of do-ko-do-ko-DON.~ Fixed: Now big notes are included in clusters.
• [x] ~For high-level Oni songs with complex groups of dense notes (e.g. (12th/16th/24th) notes mixed with (16th/34th/32nd) notes), official fumens seem to group them together even though they technically have different timings. Right now, my converter will group the 32nd notes, but treat the 16th notes as their own separate group.~ Fixed: Now anything above an 8th note will be clustered together.
• [X] Songs with BPM gimmicks. e.g. the TJA has low base BPM, but then everything is doubled/tripled except for one section. I can't remember which songs have this? Something like RNG Cinderella?
  • Maybe solved by https://github.com/vivaria/tja2fumen/pull/64/commits/1f640c1aa1fb436fe6edf421e077fdb2a41aaf00?

Fixes #41.

[vivaria]

From Discord, Yin has requested what is basically a bin2bin refresher -- basically, an option to read in an old .bin file (converted with an old version of tja2bin/tja2fumen) then update the senote types.

I think this should be pretty easy to implement as part of this PR, since:

• I already have a read_fumen function that can parse the old tja2bin-converted .bins
• The read_fumen function outputs my custom FumenCourse class, which is the exact same output as the TJA->Fumen process. So, I should be able to re-use the exact same code on both old bins and converted TJAs. :D
• I could probably make the new note type code modular, so that it can be run

[vivaria]

sakurada and yin have been helping test lots, and they've given the 👍 on this PR working as they expect 🎉