message: Remove Planet Sprite Sheets constant as they are now stored in Planet::Attributes struct
diff: @@ -162,14 +162,6 @@ namespace constants
  const std::string STRUCTURE_STATE_DESTROYED = "destroyed";
  - // =====================================
  - // = PLANET SPRITE SHEETS
  - // =====================================
  - const std::string PLANET_TYPE_MERCURY_PATH = "planets/planet_d.png";
  - const std::string PLANET_TYPE_MARS_PATH = "planets/planet_c.png";
  - const std::string PLANET_TYPE_GANYMEDE_PATH = "planets/planet_e.png";
  -
  -
  // =====================================
  // = UI STRINGS
  // =====================================
  