Release 1.3.0

What's new:

* Suppress the warning that `info/grafts` is deprecated
* Handle commits and tags that have no log messages
* Generate better JSON output (selected using `--json-version=2`). Add:
  * A prose description of each quantity
  * The quantity's value and units
  * The prefix style that should be used for the quantity
  * The "reference value" against which the value is compared
  * The "level of concern", as a floating-point number
  * The OID and description of the object in question, when applicable

Release 1.2.0

Release 1.1.0

Release 1.0.0