Drop duplicates

[mhallipelto]

Drop duplicates in holes object based on some rule.

GTK db is atleast full of duplicates. Some in different height system, some in different dates but identical data.

Duplicates with different height system

Duplicates with different dates

holes = pif.from_gtk_wfs([6677710,378534,6677991,378986], coord_system='ETRS-TM35FIn', maxholes=2000)
si = holes.filter_holes(hole_type='SI')
si.plot_map()