Massive refactor and reworking of Ruby internals:

* Add ability for scsynth to communicate back to SP
* Implement Clojure-like promises
* Add support for loading and playing samples
* Start work on new synths
* Add mod system for structuring extra features
* Add incomplete mods from previous work with Artists in case it's
  useful in the long run - not loaded by default and supported at all
* Improve support for Mac OS X (although completely unsupported atm)

Still much work to be done before a new stable release...