Avoid false positives for line and polygon hit detection

[ahocevar]

This pull request adds stricter selection criteria of candidates for hit detection on vector tiles: Currently, when decluttering is on, features from any tile will be considered for a clicked coordinate. This works well for points. But for lines and polygons, the geometries will very likely be clipped and oversimplified on any tile but the one that is rendered, i.e. contains the clicked coordinate.

By adding an additional check, we can avoid false positives resulting from oversimplified geometries outside the tile boundary.

[marcjansen]

LGTM