- bugfix: copyAllHeaders needs to handle case where INVITE could not be sent
- proxyRequestHeaders and proxyResponseHeaders now can take keyword 'all' to copy SIP headers from A to B leg without specifying them individually. Can also then selectively remove some; e.g.
proxyRequestHeaders: ['all', '-Authorization']. Note that headers such as To, From, Via, Contact, Route, Record-Route are never copied.