The next set of handles/helpers to make AnalysisBase functional in master. SG::ReadHandleKeyArray was essentially copied over from the StoreGate package and modified it for use in AnalysisBase, while Gaudi::Property was essentially rewritten from scratch. Also added some functionality to other handles and added all packages that can now be compiled in AnalysisBase.
As with the other data handles I left all the unused code in the SG::ReadHandleKeyArray for now, commented out. This makes it easier to add more functionality as needed to get the remaining packages functional. The plan is once the migration is complete to go through the remaining commented out code and either make it functional or remove it.