Implement Enum.equal?
Flags -p and -pr fails if pattern match no files

Fixes #851
Merge pull request #976 from ericmj/require

Flags -p and -pr fails if pattern match no files
Improve flag error messages in CLI

Now consistent in error messages and tries to show as many error messages
as possible before exiting.
Merge pull request #981 from ericmj/cli_switches

Improve flag error messages in CLI
Merge pull request #978 from meh/enum-equal

Implement Enum.equal?