(Search) Fix broken advanced search
(Search) Fix broken advanced search

The or'ing of SearchQuerySets in forms.py was behaving oddly, returning
results that included items in none of the sub SearchQuerySets.

Using list(chain... solved the issue.

Closes #219, closes #243

astrobin/astrobin,astrobin/astrobin,astrobin/astrobin,astrobin/astrobin