A better API

[Larpoux]

I plan to begin working on the task of cleaning the API (#493) at the end of the week.

I really want to work soon on #479 and #487, but I think that #493 must be completed before.

I would like that functional specifications being written before coding any line of code.
You (the Flutter Sound users) will approve the specifications before coding.

I suggest to create a new page on the Wiki, for that. Everybody will be able to contribute.
It would be great if you (the Flutter Sound users) begin to work on this page right now
so that a first draft will exist before the end of the week (before I start working on that).