DOCS_FROM_IDS - read ndi.document objects given an array of IDs in a single query
DOCS = DOCS_FROM_IDS(D_OR_S, DOCUMENT_IDS)
Retrieve a set of documents that correspond to a cell array of DOCUMENT_IDS.
This function is faster than similar code that searches for each document one
at a time because it combines the search into a single query.
D_OR_S is an ndi.dataset or ndi.session object.
DOCS is a cell array the same size as DOCUMENT_IDS. If the document is found, it
is provided in DOCS{i}. Otherwise, DOCS{i} is empty.