ObjDefManager, Mapgen SAPI: Huge refactoring

- General code cleanup
 - Unified object creation and loading
 - Specifying objects in APIs is now orthogonal (i.e. anything can take an ID,
   name string, or the raw table definition (and automatically registers if present

src/mg_ore.h

@@ -39,10 +39,10 @@ class MMVManip;
 
 
 enum OreType {
-	ORE_TYPE_SCATTER,
-	ORE_TYPE_SHEET,
-	ORE_TYPE_BLOB,
-	ORE_TYPE_VEIN,
+	ORE_SCATTER,
+	ORE_SHEET,
+	ORE_BLOB,
+	ORE_VEIN,
 };
 
 extern FlagDesc flagdesc_ore[];
@@ -122,16 +122,16 @@ public:
 		return "ore";
 	}
 
-	Ore *create(int type)
+	static Ore *create(OreType type)
 	{
 		switch (type) {
-		case ORE_TYPE_SCATTER:
+		case ORE_SCATTER:
 			return new OreScatter;
-		case ORE_TYPE_SHEET:
+		case ORE_SHEET:
 			return new OreSheet;
-		case ORE_TYPE_BLOB:
+		case ORE_BLOB:
 			return new OreBlob;
-		case ORE_TYPE_VEIN:
+		case ORE_VEIN:
 			return new OreVein;
 		default:
 			return NULL;