Fixed getModifierList(), and hasModifierProperty model in:
AbstractHaxePsiClass, HaxePsiMethodMixinImpl, HaxePsiField.

Also flushed out underlying methods in HaxePsiModifierList,
introduced overriding interface HaxePsiModifier that map to
Haxe annotations/modifiers instead of PsiModifier which was
Java specific. Needed changes to haxe.bnf - hence, gen/