This is based on the C-style format strings introduced in Java 5 that we can now use. When used with times, the format should be specified using URI_Templates like $Y$m$dT$H:$M:$S. TODO: See Autoplot's DataSetUtil.toString, which shows use with Calendar objects. Here is a table showing some examples:
| %9.2f | decimal with two fractional places |
| %9.2e | decimal in scientific notation |
| %.2f | decimal with two fractional places, and some number of total spaces |
| %5d | integer in five spaces. |
| $Y$m$dZ | time specification. |
create a new instance based on the Java format string.