The regexp syntax can have some nasty characters to handle quoting
correctly, in practice. In certain scenarios a double quote works well,
but it can affect readability for certain regexps. This introduces a
quoting mode that treats `/` and `|` as a double quote to make the
quoting in regular expressions more familiar and readable.
This change is introduced in a backwards compatible manner, so existing
regexp quoting is not affected.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
