AnvilStats: Added ChunkExtract mode of operation, splitting Anvil files into individual chunks.

Both original zlibbed chunks and re-gzipped chunks are output.

git-svn-id: http://mc-server.googlecode.com/svn/trunk@1223 0a769ca7-a7f5-676a-18bf-c427514a06d6

source/OSSupport/File.cpp

@@ -94,10 +94,9 @@ bool cFile::Open(const AString & iFileName, eMode iMode)
 
 void cFile::Close(void)
 {
-	ASSERT(IsOpen());  // You should not close file objects that don't have an open file.
-	
 	if (!IsOpen())
 	{
+		// Closing an unopened file is a legal nop
 		return;
 	}