Graph 3 - Swift 4.2 Support

• commit-fda0ee6: Added dynamic lookup support.
• commit-cf11d36: added dynamic member lookup for GraphJSON.
• commit-131c80d: Removed type: initializer parameter prefix.
• pr-146: GraphJSON improvements.
  • Fixed crashes on attempt to
    • serialize invalid JSON object.
    • access out-of-range subscript index.
  • Removed redundant optional chaining issue-145
  • Added Tests
• commit-4811045: Removed object: prefix from GraphJSON functions.
• commit-64c4c9a: Renamed Watch{X}Delegate to Graph{X}Delegate.
• commit-2d1c18b Updated Graph{X}Delegate delegate signature naming.
• pr-147: Major internal cleanup.
• pr-150: Added write support for GraphJSON.
  • issue-148: GraphJSON write support.
• pr-152: Added Codable support for Node.
  • issue-144: Make Entity conforming to Codable
• pr-154: Reworked Graph API completely.