Update vehicle::last_update after unfolding it.

So the game does not think the vehicle came into the reality bubble just now and does not simulate the time since the last update (the point when it was folded).
This simulation would add electricity from solar panels and water from funnels.

src/vehicle.cpp

@@ -4519,6 +4519,7 @@ bool vehicle::restore( const std::string &data )
     turn( 0 );
     precalc_mounts( 0, pivot_rotation[0], pivot_anchor[0] );
     precalc_mounts( 1, pivot_rotation[1], pivot_anchor[1] );
+    last_update = calendar::turn;
     return true;
 }