* Added hero bonuses for the composite artifacts.
* Angelic Alliance troop mixing implemented.
* Elixir of Life gives regenerating capabilities.
* Power of the Dragon Father gives spell level immunity, though that is still not implemented.
* support for 3 new artifacts:
- Ring of Vitality
- Ring of Life
- Vial of Lifeblood
* restructures creature ability preparing (creature abilities are now loaded from cr_abils.txt file). It needs further work - all changes in abilities should be moved from CCreatureHandler.cpp to cr_abils.txt as it's done in this commit (I hope it's clear how it should be done as there is an example)