Mac only: rhythm_estimator binaries included from pd_extended-0.42.5

Mac only: rhythm_estimator binaries included from pd_extended-0.42.5. Win or linux users can retrieve these externals from their platform of pd-extended (don't know if the newer version include these).

0.2: Update README.md

Pre-release with the core files and binaries. The dependencies e.g. on ClaPD and rhythm estimation will be added as submodules in the future.

Initial release 0.1

The dependencies and submodules not yet included