Switch to app domain

[dsafa]

Switching audio source isolation method to app domains.
App domain isolation simplifies many things and meets the current requirements.
With app domains, audio sources can each load their own set of libraries without interfering with other sources. They can also be unloaded / restarted if errors are detected.

Lessons learned:

• Make it simple. The original goal was to have isolation with the audio source so that they didn't leak into other audio sources, and be able to isolate errors and recover. App domains meet those requirements while keeping it simple with minimal plumbing.
• Prototype: making a prototype with the different possible solutions would have given a good sense of working within that space.
• Abstractions: Was able to switch from using WCf services to Appdomains relatively easily since interfaces were used.