fix: review findings of PR 217

- the pressures of the mover are in bar (MinCP=7.0 in the vehicle definitions), so the 0.2 the pneumatic horns
  needed was 0.2 bar; it's 2 bar now, and the tests take their pressures in bar too,
- the lamps of the ground relay and of the motor overload relays follow the pressure switch as the line
  contactors one does, TMoverParameters::MainCircuitLampsEnabled(), so the lamps of one cab go out together,
- the joint oil and fuel pump switch leaves out a pump started automatically, which ignores the switching:
  with one, it couldn't turn the other off, and showed off with both running (OilFuelPumpsEnabled()),
- the kind of the train heating switch comes from the occupied vehicle on entering the cab too, as in the
  switch commands; in a multiple unit these are different vehicles,
- CouplerForce() put the force taken back by the other vehicle on its far coupler when the vehicles faced each
  other (Couplers[1 - End] rather than the coupler it's coupled with),
- the velocity difference along the coupler axis computed once, CouplerVelocityDifference(), for CouplerForce()
  and CollisionVelocity(),
- the attachcoupler flag added without the SetFlag() call with 0, the index of the mirror moves noted as by side.

Tests: the coupler force of vehicles facing each other, the joint switch with an automatic pump, the lamps of
the main circuit, the horn and compressor pressures in bar.

tests/unit/test_couplers.cpp

@@ -424,3 +424,19 @@ TEST_CASE("couplers: automatic couplers of different control systems couple with
 		CHECK(pair.coupling() == (coupling::coupler | coupling::brakehose));
 	}
 }
+
+TEST_CASE("couplers: the coupler force of vehicles facing each other lands on the couplers holding them") {
+	// the force a vehicle takes from its coupler, the other one takes back on its own coupler of the pair, whichever
+	// way the vehicles face; it used to land on the far end of the other vehicle when they faced each other
+	auto first{automatic_wagon(5.0, "first")};
+	auto second{automatic_wagon(0.0, "second")};
+	test::pair pair{first, end::front, second, end::front, 1.0};
+	pair.run(5.0);
+	REQUIRE(pair.coupled());
+
+	pair.step();
+	REQUIRE(second->Couplers[end::front].CForce != 0.0);
+	CHECK(first->Couplers[end::front].CForce == doctest::Approx(-second->Couplers[end::front].CForce));
+	CHECK(first->Couplers[end::rear].CForce == 0.0); // nothing there
+	CHECK(second->Couplers[end::rear].CForce == 0.0);
+}