Account for different tmux versions

tmux 1.9 implemented a behavior breaking change.  When splitting or creating new
panes or windows, the current path is no longer kept.  This is addressed by the
addition of the -c parameter to the new-window and split-window commands.
Unfortunately, 1.8 does not support the -c parameter.

.tmux.1-8.conf

@@ -0,0 +1,2 @@
+bind s split-window -v # horizontal window split
+bind v split-window -h # vertical window split

.tmux.1-9.conf

@@ -0,0 +1,3 @@
+unbind c; bind c new-window -c #{pane_current_path}"
+bind s split-window -v -c #{pane_current_path}" # horizontal window split
+bind v split-window -h -c #{pane_current_path}" # vertical window split

.tmux.conf

@@ -39,13 +39,7 @@ bind-key -t vi-copy 'v' begin-selection
 bind-key -t vi-copy 'y' copy-selection
 bind y run-shell "tmux show-buffer | xclip -sel clip -i"
 
-# because the new tmux is inadequate
-bind c new-window -c "#{pane_current_path}"
-
 # be more like vim
-bind s split-window -v -c "#{pane_current_path}" # horizontal window split
-bind v split-window -h -c "#{pane_current_path}" # vertical window split
-
 bind h select-pane -L                   # left pane
 bind j select-pane -D                   # bottom pane
 bind k select-pane -U                   # top pane
@@ -65,3 +59,6 @@ set-window-option -g window-status-current-bg white
 set-window-option -g window-status-current-fg black
 set-option -g status-right '%d %b %Y @ %k:%M'
 
+# because the new tmux is inadequate
+if-shell 'test "$(tmux -V) = "tmux 1.8"' "source-file ~/.tmux.1-8.conf"
+if-shell 'test "$(tmux -V) = "tmux 1.9"' "source-file ~/.tmux.1-9.conf"