Update SDF API

[ugeorge]

Since we make an API-breaking revision, I would like to propose we take out delaySDF which seems to be redundant, and replaceable by delaynSDF.

• judging by SDF MoC semantics it makes no sense to have a separate constructor for one initial token and another one for multiple initial tokens.
• delatnSY behaves completely different than delaynSDF, and has different semantics to start with. Having the same name for so different constructors again makes no sense.
• @ricardobonna has already implemented delayCSDF and delaySADF based on the delaynSDF model.

So, my proposal is to dump delaySDF and to rename delaynSDF to delaySDF.

[ingo-sander]

OK, I agree to the changes. It makes sense, although it will break some existing examples (for instance in the book chapter). But it is good, if we have the same format as in CSDF and SADF! So, please integrate the changes!