filtercollection: change event listener: before, if a model was not in the FC.filter(model) return, the FC change event would just return. this is dumb because the model may be getting removed from the FC. fixed to return from handler only if filter(model) returns false AND the model is not already present in the FC
fixing bug in filtercollection.add where if the model already existed in the master, it would just fire "upsert" and the model would never actually be added to the FC.