Make reporter infra-structure take responsibility for measuring time and future dynamic loading of reporters about cgreen HOT 2 OPEN

Since it would be easy to forget/misuse, we would probably want to have
a flag in the reporter struct that gets set when the top-level reporter's start() is called so the
framework can output an error message when reporter->start() is called without having called
the top-level reporter's start_suite(). comments?

I can see a number of combos for calling and not calling the top-level reporter and then the specialized reporter functions. I'm not sure which we can catch and which we can't. Setting a flag would enable the top-level reporter to know that it has been called but can't force the specialised reporter to do anything. And we can't force specialised reporters to barf if the flag is not set, since we don't have a hook. But, maybe I'm misunderstanding something...

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finish_suite/test() could check the flag set by top-level start_suite/test() to look for mismatches. we could also check the flag before we run a test. maybe this won't work because of something obvious and I'm missing something ;)

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