chg and uisetup

[Jun Wu]

Excerpts from Yuya Nishihara's message of 2016-07-14 00:59:25 +0900:
> templatekw.py owns the keywords table. No problem to modify its module-level
> variable. See the other use of @templatekeyword and read the docstring.

I mean 3rd-party extensions using "@templatekeyword" will have effects
on templatekeykw.keywords at import time, which is unwanted.

> IIRC, your proposal relies on there's no import-time side effect. If we can't
> blame wonky third-party extensions, we can't preload extension modules at all.
> Therefore, we would have to stick to the current confighash method.

Right. That's what I think the right way. The new stuff here is a different
entry point. I think I can start working on it now.