Replace ugly abuse of log pages to store cached results of query pages

Replace ugly abuse of log pages to store cached results of query pages
with a table that stores up to 1000 rows for each 'expensive' special
page. This can be paged through, reducing the annoyingness of 50 result
limits on the old system.

Rebuilding the cache can be forced by adding "recache=1" URL parameter,
but this will need to be refined with some sort of controls to prevent
abuse.

Added the user realname update to the installer's updater list, also.