add defult tui and gui, allow VTTY for chvt with default of 2

misc/ui

@@ -9,7 +9,15 @@ tui () {
  sudo systemctl stop nxserver
  sudo systemctl isolate multi-user.target
  sleep 3
- sudo chvt 2
+ sudo chvt ${VTTY:-2}
 }
 
+dtui () {  
+ sudo systemctl disable lightdm
+ sudo systemctl set-default multi-user.target
+}
 
+dgui () {  
+ sudo systemctl enable lightdm
+ sudo systemctl set-default graphical.target
+}