Change ContentFeatures array to a vector

src/mapnode.h

@@ -35,19 +35,23 @@ class INodeDefManager;
 	- Tile = TileSpec at some side of a node of some content type
 */
 typedef u16 content_t;
-#define MAX_CONTENT 0xfff
 
 /*
-	Ignored node.
-
-	Anything that stores MapNodes doesn't have to preserve parameters
-	associated with this material.
-	
-	Doesn't create faces with anything and is considered being
-	out-of-map in the game map.
+	The maximum node ID that can be registered by mods. This must
+	be significantly lower than the maximum content_t value, so that
+	there is enough room for dummy node IDs, which are created when
+	a MapBlock containing unknown node names is loaded from disk.
 */
-#define CONTENT_IGNORE 127
-#define CONTENT_IGNORE_DEFAULT_PARAM 0
+#define MAX_REGISTERED_CONTENT 0xfffU
+
+/*
+	A solid walkable node with the texture unknown_node.png.
+
+	For example, used on the client to display unregistered node IDs
+	(instead of expanding the vector of node definitions each time
+	such a node is received).
+*/
+#define CONTENT_UNKNOWN 125
 
 /*
 	The common material through which the player can walk and which
@@ -55,6 +59,18 @@ typedef u16 content_t;
 */
 #define CONTENT_AIR 126
 
+/*
+	Ignored node.
+	
+	Unloaded chunks are considered to consist of this. Several other
+	methods return this when an error occurs. Also, during
+	map generation this means the node has not been set yet.
+	
+	Doesn't create faces with anything and is considered being
+	out-of-map in the game map.
+*/
+#define CONTENT_IGNORE 127
+
 enum LightBank
 {
 	LIGHTBANK_DAY,