Subject: Dial

Add RINGTIME and RINGTIME_MS variables containing respectively seconds and
milliseconds between creation of the dialing channel and receiving the first
RINGING signal

Add PROGRESSTIME and PROGRESSTIME_MS variables analogous to the above with respect to
the PROGRESS signal. Shorter of these two times should be equivalent to
the PDD (Post Dial Delay) value

Add DIALEDTIME_MS and ANSWEREDTIME_MS variables to get millisecond resolution
versions of DIALEDTIME and ANSWEREDTIME
