nopoll: * [fix] Reorganized ping frame handling to automatically respond when using   message based API (nopoll_msg_get_next) not only stream based API.    * [fix] Fixed nopoll_conn_send_ping. Added regression test (test_02-b) to check   ping support.
nopoll:
* [fix] Reorganized ping frame handling to automatically respond when using
  message based API (nopoll_msg_get_next) not only stream based API.
  
* [fix] Fixed nopoll_conn_send_ping. Added regression test (test_02-b) to check
  ping support.

ASPLes/nopoll,schmidtw/nopoll,ASPLes/nopoll,schmidtw/nopoll,schmidtw/nopoll,schmidtw/nopoll,schmidtw/nopoll,ASPLes/nopoll,ASPLes/nopoll,ASPLes/nopoll,schmidtw/nopoll,ASPLes/nopoll