Small change in behavior of ST_SimplifyVW

[nicklas]

I would like to change the threshold usage in ST_SimplifyVW from

keeping vertex points that meets

effective_area > threshold

to

effective_area >= threshold

The reason is that for ST_SimplifyVW it will more or less never make a difference, but in the more generic function ST_FilterByM like this:

SELECT FilterByM('LINESTRING(1 1 0 1, 1 2 0 5, 1 1 1 7, 1 1 1 8)'::geometry, 5);

Then I think the user expects all the three last points to be included in the answer and not only the two last points.

It is also a good thing if:

ST_SimplifyVW(geom, 5)

is identical to

ST_FilterByM(ST_SetEffectiveArea(geom),5)

So if no objections, I will do this change together with posting ST_FilterByM and reference this ticket as a breaking change in NEWS.

[nicklas]

Done in r16486