[WIP] allow sub-daily inputs to degradation_year_on_year

[kandersolar]

• Code changes are covered by tests
• Code changes have been evaluated for compatibility/integration with TrendAnalysis
• New functions added to __init__.py
• API.rst is up to date, along with other sphinx docs pages
• Example notebooks are rerun and differences in results scrutinized
• Updated changelog

Experimental PR to look at running YoY with faster-than-daily inputs. This is not necessarily a good idea and is not intended for general use.