SCUBA2: protect against bad values
SCUBA2: keep track of integration time in the summit pipeline

The duration of the data-taking part of the observation is stored in
the Frame uhdr. An easy way to keep track of the total integration
time is to just keep adding the numbers. This will result in a
per-object total integration time if maps are coadded across
observations.

Occasionally this may overestimate the total time in those cases when
the pipeline picks up data from some but not all of the subarrays.
SCUBA2: only proceed if the newimage tag is set

Maps of calibrators are made at the end of the observation which
triggers the creation of the "newimage" tag. Until then, there is no
map to analyze so wait until that tag exists before proceeding.
SCUBA2: add support for the SUMMIT pipeline

The SUMMIT pipeline needs to use the Group image to make its estimate
of texp, noise etc. Therefore add support for using the Group
image. Furthermore, the primitive must wait until a new Group image
has been created before analysis can proceed, so add logic which
checks for the relevant product and tag before proceeding.

Also warn the user that the elapsed time will be incorrect if a coadd
has been supplied when run from PICARD.
SCUBA2: add calstats and mapstats logging

Note that the beam size calculation has not yet been added so the
relevant entries will be NaN.
SCUBA2: add verbose flag, only warn about uncal data if true