#10 Better import

[Stéphane Corthésy]

In -[PKController application:openFile:], import should be done
asynchronously, particularly in case of multiple files, but also
because user could be asked, later, to confirm import (first
show him what's inside these files, then let him choose what to
import); finally, show summary of imported keys/signatures/
etc. Doable with GPGME 0.4.