create_sots did not work with numeric event codes for responses

[MaurizioSicorello]

By mistake, some of our participants were given a keyboard during a task, in which they shouldn't respond. Some of the participants pressed the key once, creating an event with code 1. This creates issues with the create_sots function, particularly with "contains(event_code{k},allcond{i}.OnsetID)", as contains() apparently does not work for numeric objects. This might be only an issue in our particular situation, but could possibly also affect studies which either have similar anomalies or have numeric event codes in some instances.