remove docgen remnants from repo, update CHANGELOG

utils/apidoc/mdn/postProcess.dart

-/**
- * Read database.json,
- * write database.filtered.json (with "best" entries)
- * and obsolete.json (with entries marked obsolete).
- */
-
-library postProcess;
-
-import 'dart:convert';
-import 'dart:io';
-import 'util.dart';
-
-void main() {
-  // Database of code documentation.
-  Map<String, List> database = JSON.decode(
-      new File('output/database.json').readAsStringSync());
-  final filteredDb = {};
-  final obsolete = [];
-  for (String type in database.keys) {
-    final entry = pickBestEntry(database[type], type);
-    if (entry == null) {
-      print("Can't find ${type} in database.  Skipping.");
-      continue;
-    }
-    filteredDb[type] = entry;
-    if (entry.containsKey("members")) {
-      Map members = getMembersMap(entry);
-      for (String name in members.keys) {
-        Map memberData = members[name];
-        if (memberData['obsolete'] == true) {
-          obsolete.add({'type': type, 'member' : name});
-        }
-      }
-    }
-  }
-  writeFileSync("output/database.filtered.json", JSON.encode(filteredDb));
-  writeFileSync("output/obsolete.json", JSON.encode(obsolete));
-}