Bugfix release 0.5.1

I've released Eyegrade 0.5.1. This version does not include any new feature, but addresses a bug that caused an empty spurious exam to be stores in the session database through the capture exam feature, when used before the answer table of the current exam were detected at least once. Eyegrade would refuse to open this session anymore. This release prevents the spurious exam to be stored in that case. Additionally, it allows Eyegrade to open the session even when such an exam made its way into the session database.

As always, you can update with git pull if you installed Eyegrade through git.