Fully implement open method, refactor others
Add checkout command, reorganize code a bit
Implement checkout command
Checkout new branch from upstream/master
Improve feedback message of checkout command
Move get_source to abstract command, remove token from code, make one-time authentication
Add missing io/console for authenticate
Make sure upstream is fetched before checkout, make issues_client inline
Add missing checkout require
Improve authentication, store username
Simplify open code
Add list command to list all repo issues, --mine flag added
Add push command
Add pull-request command