Special:Log and the logging table -- unified logging scariness!

Special:Log and the logging table -- unified logging scariness!

Replaces the ugly, often breaking, manually archived log pages with
a nice clean table which can be sorted, trimmed, viewed in pieces, etc.
You can see all logged actions by some user, or affecting some page,
and can combine the views of all all logs in one.

There are probably still some broken things in here, but I want this
committed before the patch gets any bigger.

recentchanges table is altered to make rc_namespace signed so Special:
links can be listed in it.