Port SiON demos to the new library

[YuriSizov]

The original library had quite a few cool and public demo projects (which you can find here http://wa.zozuar.org/user.php?name=keim_at_Si with their source code available).

It would be a good idea to port some of these to both test the new library and showcase its capabilities better, given how broad they are. Demos should probably be stored in a separate repo, so if you want to help with this task and the repo is not set up yet, please let me know.

As a word of warning, at least some of the demos use classes not available in the current version of GDSiON. This is because the initial version of this port focuses on the core of the library, and parts which are either used internally or needed for the project that I'm making with GDSiON. Notably, there is a whole high-level SoundObject abstraction (https://github.com/keim/SiON/tree/master/src/org/si/sound) with an extensive network of related classes which can be very helpful for end users. These need to be ported first, either as a part of this project, or as a auxiliary tool (to keep things lean).