Tmux: Crib a few things from Gary Bernhard's tmux config

tmux.conf

@@ -1,6 +1,6 @@
 # Use Ctrl-X for tmux commands
-set -g prefix C-x
 unbind C-b
+set -g prefix C-x
 
 # Reduce command delay
 set -s escape-time 1
@@ -64,5 +64,18 @@ set -g status-justify centre
 setw -g monitor-activity on
 set -g visual-activity on
 
+# This makes OS X's terminal's native scrollbar work in tmux.
+set-option -g mouse on
+
+# Fix copy/paste in vim running inside tmux. Not sure what's happening here but
+# this fixes it. Found via this blog post:
+#
+# http://www.tylercipriani.com/2013/02/09/vim-mac-osx-tmux-clipboard.html
+#
+# And it requires doing this first:
+#
+# $ brew install reattach-to-user-namespace --with-wrap-pbcopy-and-pbpaste
+set-option -g default-command "reattach-to-user-namespace -l zsh"
+
 # Local config
 if-shell "[ -f ~/.tmux.conf.local ]" 'source ~/.tmux.conf.local'