@njacazio this PR has the following:

• New decayer class that does most of the common decays (can be easily be expanded upon) using TDatabasePDG. We should also add a way to accept settings from a configuration file.
• Task that decays short-lived particles and fills a new mcparticle table with the produced decay daughters. Here I think that the datamodel needs to be looked at. I didn't manage to make the table as a new version because there seem to be some issue when using expression columns when the table produced is used directly in another task, in the same workflow. But I think that this is OK for now as a starting point
• QA task for the decayer

This workflow currently exists separately from the rest of the OTF machinery