Huge performance boost in blockhandlers, they have direct access to chunk data when blockchecking.

Also fixed vines' placement.

git-svn-id: http://mc-server.googlecode.com/svn/trunk@1278 0a769ca7-a7f5-676a-18bf-c427514a06d6

source/Blocks/BlockSapling.h

@@ -25,9 +25,9 @@ public:
 	}
 
 
-	virtual bool CanBeAt(cWorld *a_World, int a_BlockX, int a_BlockY, int a_BlockZ) override
+	virtual bool CanBeAt(int a_RelX, int a_RelY, int a_RelZ, const cChunk & a_Chunk) override
 	{
-		return IsBlockTypeOfDirt(a_World->GetBlock(a_BlockX, a_BlockY - 1, a_BlockZ));
+		return (a_RelY > 0) && IsBlockTypeOfDirt(a_Chunk.GetBlock(a_RelX, a_RelY - 1, a_RelZ));
 	}