Moved rules into their own files

Everything under `lib/rules/*` is a rules file (with the name of the rule in camelCase), re-exported into an array in `lib/rules.js`.
Moved the regular expressions from `lib/rules.js` to `lib/expressions.js`, and the rest of the variables into `lib/shared.js`.

lib/rules/noReversedLinks.js

@@ -0,0 +1,18 @@
+var shared = require("../shared");
+var expressions = require("../expressions");
+
+module.exports = {
+  "name": "MD011",
+  "desc": "Reversed link syntax",
+  "tags": [ "links" ],
+  "aliases": [ "no-reversed-links" ],
+  "regexp": expressions.reversedLinkRe,
+  "func": function MD011(params, errors) {
+    shared.forEachInlineChild(params, "text", function forToken(token) {
+      var match = expressions.reversedLinkRe.exec(token.content);
+      if (match) {
+        errors.addDetail(token.lineNumber, match[0]);
+      }
+    });
+  }
+};