Adds runtime for cocos2d-x v3.2

Copies v3.1
Supports cocos2d-x v3.2

- Changes `draw()` with the new v3.2 API: `bool transformUpdated` -> `uint32_t transformFlags`
- cocos2d-ified the API:
  - `const char*` -> `const std::string&`
  - constructors and destructors are `protected` (not `public`)
  - using `_` prefix for ivars
Updates README with v3.2 information
Merge pull request #256 from ricardoquesada/cocos2dx_v32

Cocos2dx v32
Use lastTime for AttachmentTimeline.

closes #221
Merge pull request #257 from jvasti/master

Cocos2d-iphone v.3.1 support
Fixes for the cocos2d-x v3.2 API
Merge pull request #260 from ricardoquesada/cocos2dx_v32_api_fixes

Fixes for the cocos2d-x v3.2 API
Minor license update for clarity.
Sample works with the new v3.2 API

Updates API in samples

Adds iOS and Mac projects. Convient Xcode project to test
the sample really easy.
Fixes compilation warnings
Merge pull request #261 from ricardoquesada/cocos2dx_v32_samples_fixes

Sample works with the new v3.2 API
Fix: SkeletonJson now sets mesh color if present in json.
PolygonBatch::flush crash fix
[Bugfix]
http://esotericsoftware.com/forum/viewtopic.php?f=7&t=3244
Handle DefaultSkin being null
Updated IK constraints.
Clean up.
IK constraints for spine-csharp.
Updated raptor.
Raptor example for spine-unity.