Skip source whose centroid is nan in setIsPrimaryFlag().
Propagate mask bits to coadd when rejection exceeds a configurable threshold.
Merge branch 'u/jbosch/DM-152'
remove old forced photometry implementation (DM-620)

forcedPhot.py has been replaced by forcedPhotCcd.py and
forcedPhotCoadd.py
imageDifference: fix syntax error

Now it compiles and you can get help.
Adapt to new mask bit NO_DATA replacing EDGE (DM-669)

NO_DATA means a warp/coadd pixel doesn't map to a CCD.
EDGE means a pixel is near the edge and couldn't be searched
for sources.
assembleCoadd: set good defaults for badMaskPlanes

Also, badMaskPlanes is provided by the parent class (also used
by makeCoaddTempExp), so we just need to setDefaults().
Merge branch 'tickets/DM-669'
Cleanup interpolation tasks and implement useFallbackValueAtEdge (DM-756)
respond to review comments
Merge branch 'tickets/DM-756' into mitaka
forcedPhotCcd: allow iteration over tracts when not explicit (DM-715)

We want to iterate over all tracts spanned by the data when no
tract is provided (the user doesn't want to have to look up
what tracts are spanned).  This patch determines the set of
tracts each visit touches and adds a data reference with those
tracts for each of the visit components.  This was originally
implemented for meas_mosaic, but moved here to be of more
general use, and applied to forcedPhotCcd.
make forcedPhotCcd.py, dataIds.py pyflakes-clean
Merge branch 'tickets/DM-715'