Intersection check complicates fixing intersection issues

[slhh]

Dragging a node should not be prevented when an intersection issue of the moved edges does already exist. Fixing the issues in the screenshot should not need to override the intersection protection.

@bhousel I have found the issue in the code, and constructed the example afterwards. I can try to make a pull request. Maybe, I can also address some related issues (#4769, #4745).

Btw, I can also offer a faster implementation of the geoHasSelfIntersections function. I've made some experiments, and got a reduction of execution time to approximately 40% in case of long lines.
Unfortunately, it doesn't solve #4731, there seems to be another bottleneck.

[bhousel]

Yes @slhh that sounds great - I'd definitely welcome a pull request for these 👍