Add support for multiple Event header strategies in inbound NOTIFY requests

[teles-mami]

Much like the request matching issue, a problem occurs when we want to add additional events to be processed to the existing SipPhone instance.

We cannot do this without inheriting SipPhone, which has a specific flow for processing NOTIFY requests:
validate request -> process if event is (conference | refer | presence | send bad request) -> else orphaned event error (call or transaction does not exist).

Because the middle step isso heavily cemented into the processNotify method of SipPhone, it is hard to intercept and extend this flow, and add new event packages to be processed.