Adding path_len to all stream functions in trunk

I think we need to pass along the string length to all the stream functions to maintain binary string safety through this code. This would fix annoying problems like http://bugs.php.net/39863 and a bunch of similar issues. Obviously not something we can do in 5.3 without breaking binary compatibility though. Although we might be able to do something if we assume only chars valid in the current charset is valid in file paths. Anybody have any other thoughts on this one? -Rasmus