posix_mq 1.0.0 - kinder, gentler message queues

posix_mq 1.0.0 - kinder, gentler message queues

There is one backwards-incompatible API change:

  POSIX_MQ#send returns +true+ on success instead of +nil+
  for consistency with POSIX_MQ#trysend.

This release adds the POSIX_MQ#trysend, POSIX_MQ#tryreceive and
POSIX_MQ#tryshift interfaces to avoid exceptions on common
EAGAIN errors for users of non-blocking queues.

Bugfixes: non-blocking behavior changes to a shared descriptor
in a different process are reflected immediately in the child
(this won't fix race conditions in your code, however).
Minor bugfixes for posix-mq-rb(1) and quieted warnings for
1.9.3dev.