Fix #42 flowOf doesn't respect the passed key.

[Kasheen]

Summary
This Pull Request fixes #42.

It also adds flowOf tests to DBTests_04_Flows.kt.

Notes
I noticed something strange when writing the tests.

For some reason keyById (and by extension the stateFlowOfId tests) require the id varargs to be passed as keyById("Salomon", "BRYS") instead of the way they are defined in the Person model, which is override val id get() = listOf(lastName, firstName)

I'm not sure if this is a bug. I think it's following the declaration order of the data class. I've changed the test for stateFlow, this issue was hidden before because the key wasn't being compared by the listener, but the keys being generated in the listener's operation were different from what was being generated for the parameters passed to stateFlowOfId.

I'm happy to write some docs for flowOf if you wish, but I noticed that the docs on master are ahead of the docs on the website, so these flows weren't as undocumented as I thought, infact they are quite well documented!

[Kasheen]

I've realised what's wrong with the keyOfId stuff in the tests. I had followed the other existing tests (test00_operationFlow) to construct the Adult but I think the Adult is constructed wrongly in the other tests, "BRYS" is being filled in as the first name and "Saloman" is being filled in as the last name, hence having to send those parameters to the keyOfId backwards.