Fixed another missing posix.h. Documented a little bit of main.cpp.

This was SVN commit r2016.

source/main.cpp

@@ -1039,7 +1039,9 @@ PREVTSC=TSC;
 	// crashes before the working directory is set.
 	MICROLOG(L"init vfs");
 	const char* argv0 = argc? argv[0] : NULL;
-		// TODO FIXME: why? document the need for this
+		// ScEd doesn't have a main(argc, argv), and so it has no argv. In that
+		// case, just pass NULL to InitVfs, which will work out the current
+		// directory for itself.
 	InitVfs(argv0);
 
 	// Set up the console early, so that debugging

source/ps/CStr.cpp

@@ -3,6 +3,7 @@
 #ifndef CStr_CPP_FIRST
 #define CStr_CPP_FIRST
 
+#include "posix.h" // for htons, ntohs
 #include "Network/Serialization.h"
 #include <cassert>