Review gridfix for additional features

[dkrako]

Description of the problem

There is an already existing python package for eye tracking analysis here, which has some interesting features: https://github.com/ischtz/gridfix

Description of a solution

It has some features that we are currently missing from our feature set, so it would be nice to note them all to create issues for them in a next step.

Minimum acceptance criteria

• [ ] list of gridfix features missing from pymovements