Replaces the default "Disconnect Train" (default key "V") function with a more intelligent version that prefers to disconnect a locomotive from a wagon, before disconnecting a wagon from a wagon or a loco from a loco. Makes it easier to shunt wagons with a multi-locomotive unit.

Adds a new "Disconnect Locomotive" control (default key "Shift-V") that only disconnects wagons from the player's group of locomotives. You can uncouple the train from the lead locomotive.

Also moves the disconnect message text to indicate which connection was actually disconnected!