Replace add/remove_parens with toggle_parens.
Ensure escaped slashes matched correctly.

Fixes #171
Merge pull request #174 from markalfred/mb/escaped-slashes-regex

Ensure escaped slashes matched correctly.
Merge pull request #175 from markalfred/mb/paren-toggle

Replace add/remove_parens with toggle_parens.
Merge remote-tracking branch 'upstream/master'