remove the primitive int version of setting acceptable exit codes.  due to the way java autoboxing is applied, that 'int...' method and the boxed 'Integer...' method would make a simple 'okExit(0, 2)' sort of call report as ambiguous, and that was just painfully unhelpful.

autoboxing overhead is unlikely to cause anyone a loss of sleep or productivity when adjacent to the overhead of execing, so we'll roll with it.
release version v0.3