message: Remove unused global variables from MapViewState
  These values were duplicated into an unnamed namespace for the
  `ResourceInfoBar`. They are no longer used in MapViewState.
diff: extern NAS2D::Point<int> MOUSE_COORDS;
  -
  -NAS2D::Rectangle<int> RESOURCE_PANEL_PIN{0, 1, 8, 19};
  -NAS2D::Rectangle<int> POPULATION_PANEL_PIN{675, 1, 8, 19};
  -
  const NAS2D::Font* MAIN_FONT = nullptr;
  