class Ruler
Helper class, used by [[MarkdownIt#core]], [[MarkdownIt#block]] and
[[MarkdownIt#inline]] to manage sequences of functions (rules):
- keep rules in defined order
- assign the name to each rule
- enable/disable rules
- add/replace rules
- allow assign rules to additional named chains (in the same)
- caching lists of active rules
You will not need use this class directly until write plugins. For simple
rules control use [[MarkdownIt.disable]], [[MarkdownIt.enable]] and
[[MarkdownIt.use]].