"OR" conditions squashing...

As discussed in the following comment on issue #51 (old and closed, but directly related and where this change was introduced):
https://github.com/CakeDC/search/issues/51#issuecomment-26069373

The current code would take two wholly different condition sets, which are independent OR clauses, and squash them into a single OR clause.

This change is an attempt to correct that behavior (as well as another, unrelated fix to the existing Unit tests).