search-performance branch

It looks like the other fixes I did improved matters considerably for
date search.  However, I did find some more inefficiency in the match
code, most notably in not immediately returning on a failed test.  The
date comparison code was also needlessly complicated -- all that's
really needed is to check whether the image start date is greater than
the search end date or the image end date is less than the search
start.

I've pushed those changes to the search-performance branch (and merged
that up to the current master).

-- 
Robert Krawitz                                     <rlk-FrUbXkNCsVf2fBVCVOL8/[email protected]>

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