Fix UTC Offset
Various improvements to the TSIP driver now that I have a device
Let the GPS driver tell the timing layer whether the time is good

(TSIP has a good implementation, SiRF doesn't).

If time isn't good, indicate that we're unlocked in our NTP replies
(stratum 0).

TODO: implement holdover -- if we had a good time in the past, then
stop disciplining from a bad time, let the Rb carry us, and increment
rootdisp based on how long it's been since we had sync.
Switch GPS impl from SiRF to TSIP
Let the PLL trigger jam sync if we get ridiculously far out
Config tweaks