GEOTREE2_IntListMargin
parameter for the bintree-search of the neighborhood of MESHFREE points
For the point searcch tree, assign the margin for the list of point indices in the leaf, i.e.
if the list is reallocated, how many empty places are in the list. That avoids reallocation at every time a
new point is created.
Default:
GEOTREE2_IntListMargin = 4