Edges of bursts have artifacts and need to be pruned

[scottstanie]

The stitched temporal correlation has visible burst lines:

even though this barely affects the stitched phase:

It's very likely caused by just having not a full window of data. With a half window of {x: 11, y: 5}, we see about 11/2 columns and 5/2 rows for each burst that have bad values in the temporal correlation:

but, again, this actually doesn't affect the phase in most places. Only certain areas show problems.

The fix should be either

1. don't write out a buffer equal to the half window for each processed block during the phase linking step, or
2. during stitching, morphologically erode some number of pixels equal to a half window.

(1) is probably the better solution