Now works even when the CPU is stuck in a watchdog reset loop, as it would be when the flash is totally blank.

That was a silly library, full of middleware and memory leaks. Debugging libswd was a good way to get familiar enough with SWD to write a replacement really quickly :P

This still doesn't work reliably, it seems to have the same unsynchronization bug that the old code was having. But it's much smaller and easier to understand now!

Some silly bugs are undoubtedly lurking here, but sometimes this will successfully read and write target RAM :)

Almost fast enough.. just 1.3ms more to shave off per frame.

Originally I wasn't planning on doing this, but since I need to reclaim some RAM anyway, might as well just start hacking out everything we don't need...