Off-By-One error for CORNER_COLUMN and CORNER_ROW

[jcsmithhere]

I discovered that tess-cloud is using 0-based indexing for the reference corner column and row. The convention for the TESS instrument is 1-based indexing for the pixels.

This might be related to issue #4

[barentsen]

Oh dear! Thanks for opening the issue Jeff. I expect to work on this today.

[barentsen]

Thanks again @jcsmithhere. I went ahead and merged #8, which I believe fixes the issue.

Additional verification will be useful. The PR only includes a regression test for a single coordinate/sector so far.