Added a cWorld:PrepareChunk function.

It prepares the chunk - loads or generates it and lights it.
The spawn prepare process uses this function.

src/ChunkMap.h

@@ -280,6 +280,20 @@ public:
 
 	/** Touches the chunk, causing it to be loaded or generated */
 	void TouchChunk(int a_ChunkX, int a_ChunkZ);
+
+	/** Queues the chunk for preparing - making sure that it's generated and lit.
+	The specified chunk is queued to be loaded or generated, and lit if needed.
+	The specified callback is called after the chunk has been prepared. If there's no preparation to do, only the callback is called.
+	It is legal to call without the callback. */
+	void PrepareChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_CallAfter = nullptr);  // Lua-accessible
+
+	/** Queues the chunk for generating.
+	First attempts to load the chunk from the storage. If that fails, queues the chunk for generating.
+	The specified callback is called after the chunk has been loaded / generated.
+	It is legal to call without the callback.
+	Returns true if successful, false if not (possibly an out-of-memory error).
+	If the return value is true, the callback was / will be called. */
+	bool GenerateChunk(int a_ChunkX, int a_ChunkZ, cChunkCoordCallback * a_CallAfter = nullptr);  // Lua-accessible
 	
 	/** Marks the chunk as failed-to-load */
 	void ChunkLoadFailed(int a_ChunkX, int a_ChunkZ);