Remove tweets from people in the main feed if they've already been added to a Group column. Basically I want the ability to apply negative filter. But I don't want to have to manually create a "NOT" item. I want the options to simply click a box that will NOT show Tweets from ANYONE who has been added to ANY of my group columns. This would really help me organize my Tweets. It would be the killer feature to help me make the jump from my paid Categorical.ly account to HootSuite.