Rename Right to Rights, to match RIF-CS element
Rename ExistenceDates, add parsing

Rename ExistenceDate to ExistenceDates. Add parsing of existing rights
and existenceDates elements. Add existenceDates to Collection.
Fix commenting in CommonDateElement
Rename TemporalCoverageDate>DateWithTypeDateFormat
Add Dates class and use in Activity, etc.
Remove deprecated Collection.addRelatedInfo()
Add Format; update RelatedInfo for RIF-CS v1.5
Update CitationMetadata for RIF-CS v1.5
Add change history so far