After triangulation bugfix, add minimum weight triang back as option

Now that the triang bug is fixed: https://github.com/BikeNetKit/GrowBikeNet/issues/79
Add minimum weight triang back as option with a parameter like so: https://github.com/BikeNetKit/GrowBikeNet/issues/23
The default can stay Delaunay though, because mwt is slow. But since we have the code, why not add it back, as it is consistent with the paper.

Low priority, because Delaunay seems to give identical results just faster.

At least I will update the docstring soon to note the inconssistency with the paperr (which seems totally fine).