Integrate sound effects editor

Back in 2014 (Pently 4 era), @NovaSquirrel made a sound effects editor, and I rewrote it with an improved GUI and battery save support and posted the project on in a NESdev BBS topic.

Its save mechanism was clever, writing sound effect bytecode (as described in bytecode.md) to battery RAM as ASCII-encoded source code ready for assembly with ca65. A user could open the .sav file in a text editor, copy sound effect bytecode, and paste it into a project's musicseq.s file. This was followed by the same thing in a hexadecimal encoding that the program actually used for restoring data on next run, but still ASCII so that a text editor wouldn't complain. But nowadays, we expect most Pently users to be using a more readable score input (pentlyas.md) rather than raw bytecode.

Sub-tasks:

[X] Bring sound effects editor into the tree and get it running
[x] PENTLY_USE to disable music entirely
[x] Port sfxed to Pently 5
[x] Automatically update Pently in sfxed/src from src
[x] Change output from raw bytecode to Pently score

pinobatch / pently

Integrate sound effects editor #28