Added the @tunnel command as a wrapper for @dig, for easy building in commonly used directions (n,sw, up, down, in, out etc)

src/commands/default/cmdset_default.py

@@ -70,6 +70,7 @@ class DefaultCmdSet(CmdSet):
         self.add(building.CmdUnLink())
         self.add(building.CmdCreate())        
         self.add(building.CmdDig())
+        self.add(building.CmdTunnel())
         self.add(building.CmdDestroy())
         self.add(building.CmdExamine())
         self.add(building.CmdTypeclass())