Codechange: Add base() method to StrongType to allow access to the base type without casting. (#11445)

This removes the ability to explicitly cast to the base type, but the requirement
to use .base() means the conversion is still explicit.

src/script/api/script_map.hpp

@@ -19,7 +19,7 @@
  */
 class ScriptMap : public ScriptObject {
 public:
-	static const int TILE_INVALID = static_cast<uint32_t>(INVALID_TILE); ///< Invalid TileIndex.
+	static const int TILE_INVALID = INVALID_TILE.base(); ///< Invalid TileIndex.
 
 	/**
 	 * Checks whether the given tile is valid.