Inconsistency while searching literal terms and triples with literals

[dinikolop]

When somebody wants to run searchTerms for a literal prefix that includes (part of) its datatype, they should specify the bracket(s). However, removing the bracket(s) will not return suggestions.

On the other hand, calling searchTriples for a literal with its bracketed datatype, you won't get back results. Calling with no brackets is the only way to get results:

	Returns results?
doc.searchTerms({prefix: '"a"^^<ab', position: 'object'})	Yes
doc.searchTerms({prefix: '"a"^^ab', position: 'object'})	No
doc.searchTriples(null, null, '"a"^^<abc>')	No
doc.searchTriples(null, null, '"a"^^abc')	Yes

I think there should results in all cases in order to avoid this inconsistency. What do you think @RubenVerborgh ?
I can push at #37 , since I noticed during applying requested changes there.

[RubenVerborgh]

Hmm, the assumption is that the library takes a valid RDF Term in the (old) N3.js representation. No validation is performed, so the behavior of invalid terms is undefined.

If we can fix the above as part of #37, I don't mind, but I wouldn't spend any CPU cycles on validation.