Now that sql is only used for history (not quickmarks/bookmarks) a number of
functions are no longer needed. In addition, primary key support was removed as
we actually need to support multiple entries for the same url with different
access times. The completion model will have to handle this by selecting
something like (url, title, max(atime)).
This also fixes up a number of tests that were broken with the last few
sql-related commits.
