rt-vamp wrapper

[thibaudk]

as in : https://github.com/lukasberbuer/rt-vamp-plugin-sdk
It would make a number of vamp plugins available for real time applications.

[jcelerier]

I think we should try to see with the authors of RT-Vamp sdk if they wouldn't want to port their SDK to avendish directly ? I have the impression that one could implement this SDK on top of the current avendish API directly