Add fromAscListDocIdMap to DocIdMap
Fix unnecessary type restrictions in differenceDocIdMap and liftDIM2
'deleteDocById' and 'deleteDocByUri' now work with a Set of Ids/URIs.

Removed 'deleteDocById' and 'deleteDocByUri' in favor of
'deleteDocsById' and 'deleteDocsByUri' respectively. These work with a
Set of Ids/URIs instead of single values.