Copy buffer locations as GitHub/Slack/JIRA/HipChat/... formatted code and add them
to the kill ring.  The buffer will not be modified.

With a prefix argument prompt for the format.  Defaults to `copy-as-format-default'.

To add formats see `copy-as-format-format-alist'.

For AsciiDoc customization see `copy-as-format-asciidoc-include-file-name' and
`copy-as-format-asciidoc-language-alist'.