Shifting agents get killed before wall collision

[tommy33790]

At the end of the last CPWE, we encountered the issue that agents die when they hit a wall while shifting (using tonic).

Instead they should end their action before colliding with a wall (Agent.isCollisionDetected).
If they end up in a wall anyways (i.e. go out of bounds), they should still get killed. This prevents a regression on the shifting out of bounds issue in #60

[tommy33790]

The change will propably occur in Agent.kt/goTo(...).

            // shift
            if (isShifting) {
                (0..SHIFT_EXTRA_SPEED).forEach { _ ->
                    if (isCollisionDetected) { // Will collide with wall?
                        return@performAction //<- here instead of kill()
                    }
                    if (consumeTonicForShifting()) {
                        // move and apply new direction
                        moveForward()
                        direction.apply { directionController() }
                    }
                    if (level.collisionDetected(bounds)) { // Is collied with wall?
                        kill()
                    }
                }
            }