Continue clean up on i68soyuz. Top priority is to reorganize all the HAL stuff under src/system, src/z80 and src/68k into something more coherent, maybe combining the target-specific code into some kind of static library.

Second priority on i68soyuz is to stop trying to keep src/core "clean" of target-specific code when it hurts optimization. For example, the header files should include z88dk calling convention annotations where relevant, when the z80-specific preprocessor symbols are defined. (Maybe re-organize into src/core, with a "clean" C core; an src/native, with everything that's specific to i68 and a given target, like for example string constants; and src/system, with everything that's target-specific but not i68-specific, like keymatrix read routines? It's an idea.)

Finally, the rest of the general cleanup of i68soyuz. Lots of functions to move around.

Improve error-handling in i68soyuz.

Improve handshake procedure to include stuff like feature support, configuration details, etc.

Cleanup for i68apollo. For example, moving stuff like key translation tables into config files instead of the current system of bigass match statements.

Start actually implementing new features between the two, like being able to choose which key should be treated as 'break', a low-latency mode that prioritizes packet throughput over everything else, and the ability to automatically re-synchronize in case of packet loss, among other things.

Switch crates for uinput integration, I don't care for the one I'm using.

Write XKB definitions for the supported calculators. (Optional)

I haven't even started the actual port yet--this is all just preparation for the port.