removed some more libssh2_ prefixes from private functions
removed some more libssh2_ prefixes from private functions

Made the libssh2_sftp_open_ex() deal with servers that first responds with
STATUS OK and then sends the actual HANDLE. It seems openssh does this at
times and it screwed things up. To me it seems like a spec violation...

libssh2/libssh2,libssh2/libssh2,libssh2/libssh2,libssh2/libssh2