Improve err/warn messages:

* The colon space separator is already appended by err/warn.
* Favor err(1, NULL) for malloc errors.

adding regression tests:
to verify limit on tickets progam can retrieve
by DIOCXGETRULES. Ad

tests which verify DIOCXEND works as expected, that program
can release ticket obtained b

adding regression tests:
to verify limit on tickets progam can retrieve
by DIOCXGETRULES. Ad

tests which verify DIOCXEND works as expected, that program
can release ticket obtained by earlier call to DIOCGETRULES

improvements from anton@

OK anton@, bluhm@

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