provide shunting mode

[cbries]

• adding blocks to shunting mode
• highlight blocks in shuting mode
• maybe adding route to shunting mode
• highlight routes in shunting mode
• blocks/routes in shunting mode are not recognized in ghost detection, not used in AutoMode, switches are not locked

[cbries]

• add item to shunting-mode via ctx-menu
• if no recent "shuting plan" exist, ask for a name and create a new "shunting plan", add the current item to that plan