Placate Perl::Critic
Suppress script line number from error messages

The _error function was returning a message with trailing newlines
stripped off so that when the message was croaked Perl appended a script
name and line number to it.

Now _error returns messages with a single trailing newline to make Perl
be less verbose.
Add REPOSITORY section to documentation
v0.006

  [Changes]

  - Suppress script line numbers from error messages.

  - Released on #cpanday.