* artifact manipulation in exchange window works (without switching artifacts between different heroes)

* 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)

lib/CGameState.cpp

@@ -597,6 +597,11 @@ si32 CStack::Defense(bool withFrenzy /*= true*/) const
 	return ret;
 }
 
+ui16 CStack::MaxHealth() const
+{
+	return creature->hitPoints + valOfFeatures(StackFeature::HP_BONUS);
+}
+
 bool CStack::willMove()
 {
 	return !vstd::contains(state, DEFENDING)