We want all actors and objects defined in Acedia to share
a global namespace that provides an access to important variables
(such as `Acedia` reference) and functions.
We add a `Global` singleton and `AcediaActor` / `AcediaObject`
base classes with a quick accessor to it's instance (`_` / `_()`).
Add class that can automatically perform defined tests on user request.
Developers that wish to implemet unit tests for some functionality
must extend that class (`TestCase`) and add it to the manifest,
so that Acedia can read, register and later use it to perform tests.
Anton Tarasenko