Remove a rule from this RuleSet. This accepts all the possible values that @link{getRules()} accepts. If given a Rule, it will only remove this particular rule (by identity). If given a name, it will remove all rules by that name. Note: this is different from pre-v.2.0 behaviour of PHP-CSS-Parser, where passing a Rule instance would remove all rules with the same name. To get the old behvaiour, use removeRule($oRule->getRule()).
pattern to remove. If $mRule is null, all rules are removed. If the pattern ends in a dash, all rules starting with the pattern are removed as well as one matching the pattern with the dash excluded. Passing a Rule behaves matches by identity.