Update EntityFinder interface to allow composition of iterators, and context parameter for selector
Clean out dead code
Move entity selector logic to separate class
Add context to EntityFinder invocation in entitylist selection of entities to display
Use revised entity selector syntax in list descriptions; update test cases
Update enumerated-valyue field logic to use EntityFinder,
in preparation for introducing selector capabilities for enumerated fields.
All tests pass.
Remove dead code
Add view_context parameter to FieldDescription, and update FieldValueMap and FieldListValueMap
to pass in supplied view_context.  Update EntityList and EntityView to pass context containing
RecordList and RecordView values respectively.
Add new BibEntry_type andf BibEntry_list to sitedata.  Update site data.
Review/reorganize TODO.
Work in progress: renaming; tests pass
Work in progress: renaming; tests pass
Renamed fields in field descriptions for greater consistency/clarity.  All tests pass.
Tidy up some field description files in sitedata
Added field restriction information for BibEntry fields to sitedata
Use field selector in FieldDescription to restrict enumerated fields to those which might be used
with the entity type that is taergeted by the current view.  C
hanges to entityedit logic to accommodate access to current entity for enumeration selectors.
Update tests to cover new enumeration functionality.