Finish off --help output about invoke HOT 2 CLOSED

Finally got around to fixing that. Sadly no existing lib had quite what I wanted (...) but in the end it was simple enough I just did it by hand. May roll into Clint later?

Only thing left is to test/tweak ordering of the help lines (which I thought I had, maybe not?) e.g. version comes at the top now and should probably be at the bottom (? or should version and help always be at the top?)

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Herp derp, the ordering was messed due to case sensitivity in cmp. Fixed; went with case insensitive sorting overall (so that e.g. M might come between l and o) and in situations where case is the only difference (e.g. V vs v) had lowercase win out, as that just "feels" right to me for some reason despite cmp behaving opposite (due to ASCII codes I believe).

from invoke.