thanks for this wonderfull and very usefull app.
A small suggestion: Some URLs for CALDAV are quiet lengthy, e.g. when using OWCLOUD on a own hosted system at home.
As an alternative to entering CALDAV/CARDDAV URLs manually using the on-screen keyboard, reading and scanning a QR-image would be very helpfull. The QR may also contain the user credentials (username/password)
This would make configuration a breeze esp. for people that are not that technically affiliated.