v0.1.15-ag

enhancements:

• d7bf7df websockets work-around: socket tx buffer 1k -> 4k
• 6e29865 exit with failure if main() promise is rejected
  • c9423d1 export mxRejectedStatus as fxPromiseIsRejected()
• 1882225 http: support async replies

bug fixes:

• 2619ea4 keep main loop running while promise jobs are pending
• 6e54be5 fix hang in delete machine: don't unref main context