Consider annotating remaining text spans

[michelole]

We have access to documents of 300 patients, each patient classified according to the 13 eligibility criteria. We plan to use that as input for machine learning approaches.

However, we also got access to annotated text spans of 10 patients. This is not enough for machine learning, but it could be expanded with the help of @kasac.

Annotation software was provided by the organisers.

[michelole]

Definitely not feasible til the n2c2 deadline, could be an interesting enhancement for the future.