frontend: survey generation weird at corners

[ES-Alexander]

Current behaviour

Corners do not seem to be properly accounted for in the survey generation polygon, resulting in some long diagonal segments that aren't aligned with the intended survey orientation, which is unintuitive and undesirable behaviour.

Expected or desired behaviour

Where relevant, the long diagonals should be replaced by lines either following the polygon border, or cutting across just a corner of it (instead of moving all the way to the far side of the polygon).

Prerequisites

• [X] I have checked to make sure that a similar request has not already been filed or fixed.

[rafaellehmkuhl]

I could swear I had fixed that. Thanks for reporting.