A default tick format for an ordinal scale with temporal values in local time

[mbostock]

Per the code:

TODO We need a better way to infer whether the ordinal scale is UTC or local time.

Currently we support the default time format for ordinal scales when we can infer a time interval, but we always use UTC time. How could you indicate that you want to show the times in local time? Or should this be based on supporting an arbitrary time zone at the Plot level? #531 Alternatively, should we expose Plot’s default time formats as reusable implementations?