build(aio): refactor dgeni packages

This is to tidy up the `author-packagse`, which currently duplicates a
lot of the configuration in the main packages. We need to
DRY this up so that we don't fall foul of a change in one being missed in
the other.

aio/tools/transforms/angular-base-package/processors/checkUnbalancedBackTicks.js

@@ -0,0 +1,33 @@
+var _ = require('lodash');
+
+/**
+ * @dgProcessor checkUnbalancedBackTicks
+ * @description
+ * Searches the rendered content for an odd number of (```) backticks,
+ * which would indicate an unbalanced pair and potentially a typo in the
+ * source content.
+ */
+module.exports = function checkUnbalancedBackTicks(log, createDocMessage) {
+
+  var BACKTICK_REGEX = /^ *```/gm;
+
+  return {
+    // $runAfter: ['checkAnchorLinksProcessor'],
+    $runAfter: ['inlineTagProcessor'],
+    $runBefore: ['writeFilesProcessor'],
+    $process: function(docs) {
+      _.forEach(docs, function(doc) {
+        if (doc.renderedContent) {
+          var matches = doc.renderedContent.match(BACKTICK_REGEX);
+          if (matches && matches.length % 2 !== 0) {
+            doc.unbalancedBackTicks = true;
+            log.warn(createDocMessage(
+                'checkUnbalancedBackTicks processor: unbalanced backticks found in rendered content',
+                doc));
+            log.warn(doc.renderedContent);
+          }
+        }
+      });
+    }
+  };
+};