Support timeline queries across datasets
This MR implements a timeline query across multiple datasets.
The trick, which I'm not 100% sold on is to find the 'best' dataset, using the same logic as before, then match all other datasets that have the same suffix, under the assumption that they represent the same sort of data, e.g. if you find O3a_16KHZ_R1
as the best, and O3b_16KHZ_R1
also contains data in the interval, return that as well.
@martin.beroiz, is there a better way to determine that two datasets contain 'the same sort of data' just across two different epochs?
Closes #85