No error message displayed after trying to give points with three digits after comma.

Problem: When trying to add points having three digits after coma, noting happens.

Possible reason: Points with three digits after coma are not supported.

Steps to reproduce:

1. Edit an exercise: https://markman.cosy.sbg.ac.at/\<exerciseID>/edit/
2. Put 0.025 to the points field of a student.
3. Click Eintragen.
4. The website stays at https://markman.cosy.sbg.ac.at/\<examID>/save/

Assumed correct steps:

1. Edit an exercise: https://markman.cosy.sbg.ac.at/\<exerciseID>/edit/
2. Put 0.025 to the points field of a student.
3. Click Eintragen.
4. Error message displayed saying that points having three digits after coma are not supported.

Additional comment (maybe should become a separate issue): There is an inconsistency of the addresses above: <exerciseID> vs <examID>.