filter out all search results with no TTH root

[OrangeSlice]

having an option to filter out all search results with no tth root would be nice so a source with a TTH root would always be selected as ensuring the dl queue entry would also have a TTH root.

[GargoyleMT]

There are some requests for a search filter already, this would be a good feature to glob into that one.

Shareaza seems to remember all search results for the current search, and allow you to apply filters on the fly (so no results are permanently discarded), that's what I had in mind...