Factor min dist filtering into a sub-function
Intended to allow iterative filtering, for instance to re-filter by an auto calculated mindist once initial avg distance is computed. Introduces an extra loop through all the points, which is a con.
Draft auto-calculate min dist filtering.
Pre-calculate scale based on projected min/max geo coordinate points;
figure that any segments with a length less than the buffer width are not much use at the selected scale, and auto-set mindist to that size. In addition to smoothing the route, this helps avoid artifacts of noisy-angle segments.
Not tested with linear/ring shapes. Not tested with markers (important; filtering tends to reduce calculated route length, which could throw off marker locations.)
Interface should have an explicit "auto" mindist setting as an alternate to manual filtering