nc count checking is too strict

[mayoneez]

Hi and thanks a bunch for this wonderful library.

I noticed that it checks that the nc (nonce count) given by client must be greater than previous value. This check is too strict and causes login window to pop up on client way too often. Instead, it should only check that the same nc number is not reused. Client cannot ensure that its requests arrive to the server in order so checking for ascending order is too strict.