Further header cleanup and a few updates

Updated llstring to current linden
Further linden_common cleanup
Header cleanup
Raised banlines to 5000 as per linden server change
Included missing llmediaentry.cpp file
Minor whitespace changes here and there

indra/llmessage/llbuffer.cpp

@@ -28,7 +28,6 @@
 
 #include "linden_common.h"
 #include "llbuffer.h"
-#include <iterator>
 
 #include "llmath.h"
 #include "llmemtype.h"