Added PAM_TAC_PACKET_DEBUG to enable Cisco IOS style packet debugging enabled by debug_packet pam module option
Properly implemented the use of GETDATA AUTHEN/REPLY packet type using PAM converse function to request data from the user
Implemented pam_sm_chauthtok function to allow tacacs password change (supported using login=login module config to force TAC_PLUS_AUTHEN_TYPE_ASCII