Matvey Arye 662be94d69 Add the first(value, time),last(value, time) aggregates
Add the first and last aggregate functions, which allows for getting
the first and last value, by time, per group. Addresses issue #30.
2017-05-16 09:46:49 -04:00
..
2017-04-23 19:45:46 -04:00