Freeze if filter geometry is very complex

[kannes]

The plugin will freeze QGIS (at least for a while) if a complex filter geometry is used, e. g. that of Canada in the "world" easter egg's dataset (NE50?).

Maybe count the number of vertices in the selected geometry/-ies, when the user wants to define a filter from that, and only allow its usage if the total is reasonable low?

Maybe add a warning dialog if the geometry if complex and allow the user to cancel?

[kannes]

Complex geometries are also an issue if saved because they lead to huge entries in the QGIS3.ini.

E.g. Germany from world is a ~3 million characters long line...