Add Rule.parser property for custom rules to specify which Markdown parser output they use, honor it strictly, and add full type support.

lib/md047.js

@@ -10,6 +10,7 @@ module.exports = {
   "names": [ "MD047", "single-trailing-newline" ],
   "description": "Files should end with a single newline character",
   "tags": [ "blank_lines" ],
+  "parser": "none",
   "function": function MD047(params, onError) {
     const lastLineNumber = params.lines.length;
     const lastLine = params.lines[lastLineNumber - 1];