Allowing a new process instance to be created by "pick onAlarm until"

["Ugo Corda" <UCorda@SeeBeyond.com>]

Currently the spec does not allow a Pick with createInstance=yes when
alarms are specified. I don't see a good rationale for having this
restriction in the case onAlarm specifies a particular time for the
associated activities to occur ("until" case). 

Relaxing this restriction would be useful when we want a process
instance to start at a particular time, possibly on a periodical base.
An alternative way of achieving the same effect would be by defining a
receive from a "partner" representing the deployment environment, and
having the environment itself send a message at the appropriate time.
But I think it would be more clear if we use the pick-onAlarm construct
instead.

Unless somebody shows me that the idea does not make sense, I'll file a
formal issue for it.

Ugo