Add report suggestion when an app contains message types that differ only by pointer/non-pointer.

[jmalloc]

For example, if within a single app, one handler uses the message type Foo{} and another uses the message type &Foo{} this should produce some kind of "warning" suggestion at the test level.

[jmalloc]

This could even cause every test to fail unless you specifically allow it by calling something like test.AllowSimilarMessageTypes()

[jmalloc]

See also #28