Remove old .tmux.conf

Whatever systems I have that don't have the latest tmux, I'll cope.
I can create my own symlinks, for Darwin's sake.

dot_tmux.conf

@@ -1,21 +0,0 @@
-set-option -g default-shell /usr/bin/fish
-
-bind-key h select-pane -L
-bind-key j select-pane -D
-bind-key k select-pane -U
-bind-key l select-pane -R
-
-# nested tmux, obey me
-bind-key a send-prefix
-
-# Avoid the annoying bit of delay when using the control character
-set -g escape-time 0
-set -g renumber-windows on
-
-# Show a visual bell, even on other windows
-set-window-option -g visual-bell both
-set-window-option -g bell-action other
-
-# Set up the window visuals
-set -g window-status-style bg=yellow
-set -g window-status-current-style bg=red,fg=white