mode bits incorrect for trigger modes and powerdown

[sages]

Mode selection requires multiple calls to configure mode. Individual bit manipulation of mode register precludes selecting specific modes unless multiple calls made to change mode bits.
In trigger mode to actually power down you need to call setShuntMeasDisable as well as setModePowerDown to enter power down mode.
similar on recovery from power down mode to trigger mode requires calling setShuntMeasEnable, setBusMeasEnable, setModeTriggered then a suitable delay to allow all of the triggered conversion to finalise.

Would be infinitely simpler to enumerate all seven mode and just select the required mode with one function call.