handle XEP-0203 (Delayed Delivery) and use it when forwarding unread messages via adhoc commands. Fixes #4347

use spec version instead of program version to determine which spec to use for notification-daemon. Fixes #4126

don't remove contact instance when we remove last event if a chat is stil opened, but when we close the window. Should fix #4272

Replace METH_VARARGS with METH_NOARGS, discard win32 ifdefs (it's no more compiled on win32 anyway).

prevent traceback when connection is lost while waiting for user to accept plain connection or ssl certificate. Fixes #4285