Expose enums
Blocked when upstream queue come at limit
Add no mask option
Change Random field from static to instance
Add MaskDecoder class
* Add largeMessage test case.
* improve and bug fix MockServer
* Add largeMessage test case.
* optimize mock server main loop
* #7 Mask key position is wrong. move to extend payload length field after.
* fix MockServer reliability
* fix CLOSE state handling
* improve reduce frame buffer copy