Add support for read timeout

  the wait method now has a third argument: timeout on read, this
  setting will be set temporally when used. if timeout is set
  to 0 (default) then no timeout is applied (BC).

  This feature is useful if you want to add timeout on RPC calls
Improve timeout management to use native stream_select function
Merge pull request #66 from ekino/add_timeout_read

Add support for read timeout