- short command usage output now lists subcommands instead of flags for
parent commands
- mistyping a subcommand now results in a non-zero exit status
- requesting `--help` or `-h` for any command now prints help docs on
stdout and exits with 0
This is due to the fact that `gh completion` can be programatically used
during shell startup and we definitely don't want to
1. slow down people's startup time
2. show any upgrade notice until the user has invoked `gh` manually
For `net.DNSError`, the full error message can be scary. Instead, print "error
connecting to HOST" and hint that the user should check their internet connection
or githubstatus.com.
When $DEBUG is set, the full DNS error is printed like before.
Fixes#206
