Support shortened command & dir name in xterm title plugin

This allows the user to see only last level of the current path (if dirname is longer than 8 chars),
and only first word of the ongoing command line if it's longer than 8 chars.

plugins/available/xterm.plugin.bash

@@ -1,18 +1,28 @@
 cite about-plugin
 about-plugin 'automatically set your xterm title with host and location info'
 
+
+short_dirname () {
+    local dir_name=`dirs -0`
+    [ "$SHORT_TERM_LINE" = true ] && [ ${#dir_name} -gt 8 ] && echo ${dir_name##*/} || echo $dir_name
+}
+
+short_command () {
+  local input_command="$@"
+  [ "$SHORT_TERM_LINE" = true ] && [ ${#input_command} -gt 8 ] && echo ${input_command%% *} || echo $input_command
+}
+
 set_xterm_title () {
     local title="$1"
     echo -ne "\033]0;$title\007"
 }
 
-
 precmd () {
-    set_xterm_title "${SHORT_USER:-${USER}}@${SHORT_HOSTNAME:-${HOSTNAME}} `dirs -0` $PROMPTCHAR"
+    set_xterm_title "${SHORT_USER:-${USER}}@${SHORT_HOSTNAME:-${HOSTNAME}} `short_dirname` $PROMPTCHAR"
 }
 
 preexec () {
-    set_xterm_title "$1 {`dirs -0`} (${SHORT_USER:-${USER}}@${SHORT_HOSTNAME:-${HOSTNAME}})"
+    set_xterm_title "$(short_command $1) {`short_dirname`} (${SHORT_USER:-${USER}}@${SHORT_HOSTNAME:-${HOSTNAME}})"
 }
 
 case "$TERM" in