Initial commit. Library separated into two parts: interface layer and
implementation library. Application have to use only interface to work
with engine. Currently only static loading of implementation library works,
but i've done derelict-style loader for dynamic loading awaiting proper
shared library support in D.

Added:
* IBoreyCore - core interface, which represents engine instance.
* SimpleBoreyCore - one windowed simple releazation for IBoreCore.