[nixio] Test special cases for annotations
[nixio] Test special cases for annotations

Tests writing (and reading back) empty lists, empty tuples, and list of
strings. An empty tuple is read back as an empty list.

JuliaSprenger/python-neo,apdavison/python-neo,samuelgarcia/python-neo,NeuralEnsemble/python-neo,INM-6/python-neo,rgerkin/python-neo