message: Mark `SeedLander` default constructor as deleted
  It doesn't seem to make much sense to allow the SeedLander to be default
  constructed. For it to be valid, it needs a location, and there is no
  sensible default for that.
diff: @@ -9,7 +9,7 @@ public:
  typedef NAS2D::Signals::Signal2<int, int> Callback;
  public:
  - SeedLander() = default;
  + SeedLander() = delete;
  SeedLander(int x, int y): Structure(constants::SEED_LANDER, "structures/seed_0.sprite", CLASS_LANDER),
  mX(x), mY(y)
  {
  