Add controls to allow user to set values of API parameters maxdist and maxdistrel

[ojalaquellueva]

Before submitting coordinates, users should be able to adjust parameters maxdist and maxdistrel. The two parameters adjust the thresholds required for a point to be flagged as a possible centroid. "maxdist" is the distance in m of the submitted point from the polygon centroid (current default=1000). "maxdistrel" is the relative distance to the centroid—relative to the farthest possible point from the centroid along the polygon perimeter (current default=0.002). Parameter "maxdist" is a positive integer on range [0:4500000]. Parameter "maxdistrel" is a positive decimal value on range [0,1].

[ojalaquellueva]

You can use sliders for both parameters, similar to the match threshold control for the TNRS. However, these values must be set at the top, before submitting the coordinates.

[ojalaquellueva]

Correction. For parameter maxdist, make the allowable range [0:100000], with default 1000 (=1000 m). There is no reason for the maximum value to be any higher than 100 km.