osc/ctl : use osc incoming data as controllers

[reno-]

I just reloaded span and the loading time for the span.maxpat is at least six seconds on my mbp i7.
After investigations, the guilty is the [poly~ mappolytest2 20] which need 5 secondes to instanciate the 20 voices for incoming osc dataflow.

[reno-]

I think that we need to keep a span patch as light as possible. That's true that we need some mappings functions, but I might prefer to have all the mappings in only one place, and use this central mapping for osc incoming dataflow.

Maybe we could first just record osc addresses and messages type in the span dict.
And after allow user to add it to the namespace and use it in a mapping. This workflow could be really quick but it might be important to separate dedicated functions.

What do you think about?