~/.tmux.conf: Enable emacs keybindings in tmux commands

Including search!

.tmux.conf

bind-key -n F7 select-window -t 6
bind-key -n F8 select-window -t 7
set -g status-keys emacs
bind-key -T copy-mode-vi ? command-prompt -i -I "#{pane_search_string}" -p "(search up)" "send -X search-backward-incremental \"%%%\""
bind-key -T copy-mode-vi / command-prompt -i -I "#{pane_search_string}" -p "(search down)" "send -X search-forward-incremental \"%%%\""