apenwarr-redo

minimal/do: add redo-whichdo support and internal unit tests. Adding redo-whichdo wasn't so hard, except that it exposed a bunch of mistakes in the way minimal/do was choosing .do files. Most of the wrong names it tried didn't matter (since they're very unlikely to exist) except that they produce the wrong redo-whichdo output. Debugging that took so much effort that I added unit tests for some functions to make it easier to find problems in the future. Note: this change apparently makes minimal/do about 50% slower than before, because the _find_dofiles algorithm got less optimized (but more readable). It's still not very slow, and anyway, since it's minimal/do, I figured readable/correct code probably outweighed a bit of speed. (Although if anyone can come up with an algorithm that's clear and works better, I won't turn it down :) I feel like I must be doing it the hard way...) 2018-10-31 03:33:47 -04:00			`exec >&2`
			`./do.test`