Add Cancel-Button while importing data

Import the following file ("display only" if you dont want to mess up your database) to find out why Locus needs a "Cancel" button during data import:

http://www.alpenzorro.de/_cache/zorro.zip

I am not complaining about speed or anything... it's a lot of data after all. And if you let the import finish (5 minutes on my phone), Locus handles it surprisingly well (1 fps zooming obviously, but the rest is fine). It would still be nice to be able to abort imports... otherwise any random link on any web page can basically kill Locus. You can't really know beforehand if you click on a hundred points or on a million.