MazamaTimeSeries 0.3.0

Updated dependencies:

• MazamaCoreUtils 0.4.15 => 0.5.2

• All mts_~() functions that return an mts object now return an empty mts when an empty mts is used as input. This prevents breaks in the middle of pipelines so that "emptiness" only needs to be checked at the end.

• All sts_~() functions that return an sts object now return an empty sts when an empty sts is used as input.