Run Aqua VM in background

[coder11]

Aqua VM interpreter runs on the main thread. It may cause performance problems noticeable to browser users. An incoming particle can potentially block the entire application UI and there is no mechanism to prevent that.

There should be an option to run particles' script interpretation in a separate thread using webworkers in browser and worker threads in nodejs.

The implementation should consider the following:

1. The execution strategy should be configurable
2. Both nodejs and browser should be supported with no difference to JS SDK consumers
3. The code should be reused between nodejs and browsers as possible

This issue depends on the integration of the async AVM #73

[coder11]

Implemented in #111