for NAF: check that nr terms == nr of tokens

[dafnevk]

NAF has a text layer for tokens (words) and a terms layers for terms, where in principle multiple tokens (New York) could form one term (New_York). However, as e2e works on token level but should be mapped to the terms, it only gives correct output if there are no multi-token terms. This is the case if we use stanza for creating the term layer.
We should check that this is the case if we read in NAF.