fish: Fix vim function error when on ¬mac systems.
fish: Don't export internal vars in vim.fish.
fish: open needs to reattach-to-user-namespace.
tmux: Usability changes.

tmux: Aggressively resize sessions.
tmux: Renumber windows to maintain sanity when closing windown in
    between others.
tmux: Don't trigger copy mode when dragging with the mouse.
tmux: Don't take over the entire status bar for alerts about activity.
tmux: Add status bar colours!