Improve test coverage for AbstractMethodMockingControl

This commit improves the test coverage for AbstractMethodMockingControl
by introducing tests that verify expected behavior for:

 - reentrant method invocations via public methods
 - reentrant method invocations via private methods
 - test methods that do not set expectations or invoke playback()
 - test methods that throw exceptions

For a more complete discussion of "after" vs. "after returning" advice
within AbstractMethodMockingControl, see the Javadoc in the tests.