closes #66

This was the version that introduced the crossmatch function.

The function `ligo.skymap.postprocess.find_injection.find_injection_moc`
was renamed to `ligo.skymap.postprocess.crossmatch.crossmatch`.

Leo P. Singer authored Feb 24, 2020 and Leo P. Singer committed Feb 26, 2020

- ra: sexagesimal hours, minutes, and seconds
- dec: sexagesimal degrees, minutes, seconds
- a, b, pa: decimal degrees to the nearest hundredth of a degree,
  which is slightly less than arcminute precision

This reverts commit 880581d3

Leo P. Singer authored Feb 20, 2020 and Brandon Piotrzkowski committed Feb 21, 2020

Fixes #64.