building-comparison: check eubucco coverage calculates with sea area

[Gigaszi]

The function get_eubucco_coverage_intersection_area compares the area of the eubucco boundaries, which are on the coastline, with the dashboard bpolys, which are the sealine.

[hn437]

Due to this, the bpolys of states with lot's of coastline and islands like denmark is only covered by eubucco for less than 50%, eventhough the land mass is entirely covered. Due to the coverage of <50% the oqapi calculation is aborted