Allow more than one group to be selected as a filter.
Primary motivation: SF wants SF & Køpi feed. Secondary: Actually makes sense to list a few groups together on a page. "I'm looking for events in x,y or z which are local to me and I like"
Primary motivation: SF wants SF & Køpi feed. Secondary: Actually makes sense to list a few groups together on a page. "I'm looking for events in x,y or z which are local to me and I like"