Fail fast if invocation matches never expectation

[floehopper]

TODO

• [x] Come up with a version of this that emits a deprecation warning rather than actually changing the behaviour.
• [ ] Ensure all the relevant documentation is updated, e.g. method dispatch in README, class docs for Mock, and docs for any relevant methods.
• [ ] Update commit note(s) to reference being consistent with the behaviour described in the following test which was added in https://github.com/freerange/mocha/commit/d3583772c3fd878a567a0b04750d98ff7d079358

https://github.com/freerange/mocha/blob/f899c034a6f1472788936f2a889ae8d5c323f1de/test/acceptance/expected_invocation_count_test.rb#L202-L214

Previously when an invocation matched an expectation which did not allow invocations (i.e. Expectation#never had been called on it), but the invocation also matched another expectation which did allow invocations, then the test would not fail with an unexpected invocation error.

This was happening because neither the if condition was true, because the "never" expectation was not returned by ExpectationList#match_allowing_invocation, but the other expectation allowing expectations was returned. Thus Expectation#invoke was called on the latter and Mock#raise_unexpected_invocation_error was not called.

This behaviour was confusing and had led to a number of issues being raised over the years: https://github.com/freerange/mocha/issues/44, https://github.com/freerange/mocha/issues/131, https://github.com/freerange/mocha/issues/490 & most recently https://github.com/freerange/mocha/issues/678. Previously I had thought this was a symptom of the JMock v1 dispatch behaviour (which might still be true) and thus would be best addressed by adopting the JMock v2 dispatch behaviour (https://github.com/freerange/mocha/issues/173). However, having considered this specific scenario involving a "never" expectation more carefully, I've decided to try to fix it with the changes in this PR.

Now a test like this will fail with an unexpected invocation error:

mock = mock('mock')
mock.stubs(:method)
mock.expects(:method).never
mock.method

unexpected invocation: #<Mock:mock>.method()
unsatisfied expectations:
- expected never, invoked once: #<Mock:mock>.method(any_parameters)
satisfied expectations:
- allowed any number of times, invoked never: #<Mock:mock>.method(any_parameters)

Closes https://github.com/freerange/mocha/issues/678. Also addresses https://github.com/freerange/mocha/issues/490, https://github.com/freerange/mocha/issues/131 & https://github.com/freerange/mocha/issues/44.