Allow global default search result sorts

Users could define these from Logged in -> Settings -> Search options
basically forever, but you couldn't set a global default.

We keep the old hard-coded-default of id, ASC despite it being one of
those "almost never what you want" since it means you always see your 5
year old bugs first. Let admins give their users a saner sort
(especially helpful on links in Quick Search).

When setting your user search prefs or creating a new search from
scratch, use the defaults rather than id/ASC.
Merge branch '4.2/configurable-search-order' into 4.2-trunk