[xmonad] new contrib module: XMonad.Actions.DynamicWorkspaceOrder

Hi all, I've pushed a new contrib module which uses extensible state to keep track of a current workspace ordering, with a way to swap two workspaces, and ways to get DynamicLog and CycleWS to use the current workspace ordering instead of the order of workspaces in the user's config. This way I can reorder my workspaces any way I like on-the-fly, have them show up in that order in my status bar, and cycle through them in that order with CycleWS-like keybindings. -Brent