This change introduces a new command that, like lengthen, move, resize, and
shorten, is intended to move and/or resize a record, but instead of taking an
interval, will take an absolute date/time.
This command is useful because it removes the need for the user to calculate
the time intervals to shorten / lengthen a record by. For example, if the user
accidentally forgot to stop tracking an interval before starting a new one,
but new they stopped working at a specific time, it is easy to simply modify
the end time of the interval that they had forgotten to stop.
