Multiaccount interactions from a column

[ShadowJonathan]

This is related to #491, but is a proposed solution;

Have each column have an optional setting which either;

• forces all interactions in that column (reply, fav, boost) to come from one account, selected from the dropdown
• forces all interactions to pop-up with an account to choose from, before doing that action, with an "always ask" option in the dropdown

This would allow columns to be simply feeds from multiple accounts, and streamline interactions.