While launching an new portal component test, a "Duplicate tpc_begin
calls for same transaction" error was raised. This was coming from
the finally clause in runUnitTestList, in the commit of
ProcessingNodeTestCase.unregisterNode.

After long investigations, we found out that a new app was created
while the transaction was still opened. After more investigations,
it was discovered that the runUnitTestList code was raising an
exception, and this exception was hidden by the exception in the
finally close.

So this patch provides:
1 - a cancellation of the transaction to avoid "duplicate tpc_begin
    calls" error.
2 - a print of the exception before the finally clause is launched
    to make sure we have information on possible exceptions

Base_checkPermission script API is not so nice. With it's name, we would expect it
doing checking on the object on which it is called. Instead we must give a path. This
would need to be improved. Also we will ned to clean proxification

Instead of getting all destination uids, run the search and activate with
destination_related_uid.

When MailMessage portal type is not installed, then temp mail messages will use
this class. The plan is still to remove the class, but for now just remove this
method that can overload Event.send

This rely on a change in erp5_base where Event_send does nothing and MailMessage_send sends email instead, otherwise mails will be sent for all started events.

We only want to send an email for mail message portal type

We always generate the event upon start. User can pass another transition not to generate the event.

Resource.asPredicate was broken and Base.asPredicate is useless.