WinGui: Currently hb_title_s.path is directly marshalled as string. But this isn't good because path is UTF-8 encoded C string, and fails with non-ASCII characters. To fix this, treating path as raw UTF-8 byte array and converting to string in ConvertTitle() method should work. Patch Submitted by Taihei, review 760

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6404 b64f7644-9d1e-0410-96f1-a4d463321fa5