HDF: Update parser classes

Renamed IHndfParser to IHDFParser and added some documentation.

CHndfParser:
o fixed skipNode function -- now it should correctly skip node with all it's
subnodes.
o minor aesthetics
Core: Update CModelLoader

.. to accomodate for rename of HDF parser header.
Delete HavokMagicSpells.h
Rename folders according to new convention
Docs: Add hrengin conventions document
Docs: Move obsolete documens to `obsolete` folder
Graphics: Remove duplicates

Some time ago those were intended to be rewritten into OSG wrapper, and
since then forgotten.
Physcis: Rename hrenginphysics to physics-bt
Audio: Create OpenAL Soft wrapper

This is only a basic wrapper, but it provides almost the same
functionality as the previous BASS wrapper.

- threaded sound play
	still needs some work, currently consumes excessive cpu power
- WAVE RIFF loader
	no other formats
- sounds are still hardcoded