Ability to capture high-resolution timestamp data in date filter

This will allow the user to set "retain_hires" to true for ISO8601 timestamps, and capture the micro- and nano- second timestamp resolution into new fields. Joda will still truncate the timestamp at milli, as usual, but now users can sort on the secondary field, or use the original hires timestamp for their purposes. Looking for feedback on whether regex capture is a decent strategy, variable/field names, etc.