[Dovecot] APOP and CRAM-MD5 in checkpassword module

Still a bit more fixes. My coding TODO list is again empty. Whether it is possible to add APOP and CRAM-MD5 in the checkpassword-module? Original qmail-popup is able APOP, and smtp-auth patch (http://www.fehcom.de/qmail/smtpauth.html) can use CRAM-MD5, accordingly, vckpw from vpopmail understands both these of a method. Very much would be desirable, that these two methods were in dovecot (in chackpassword-module).

М. Alhimenko.