Core/Pets: merged funjoker's new Pet Slot system

* fixed packets and handling for stable master
* fixed Control Pet / Demon handling
* corrected wrong trainer spell for the Control spells
* Added base support for Assist behaivior
* corrected action bar layout
* Hunter Pets will now have the same level as their tamer (patch 4.1 change)
* corrected health stats for pets

src/server/scripts/Spells/spell_pet.cpp

@@ -51,11 +51,6 @@ enum WarlockPetCalculate
      SPELL_WARLOCK_PET_SCALING_03       = 34957,
      SPELL_WARLOCK_PET_SCALING_04       = 34958,
      SPELL_WARLOCK_PET_SCALING_05       = 61013,
-     ENTRY_FELGUARD                     = 17252,
-     ENTRY_VOIDWALKER                   = 1860,
-     ENTRY_FELHUNTER                    = 417,
-     ENTRY_SUCCUBUS                     = 1863,
-     ENTRY_IMP                          = 416,
      SPELL_WARLOCK_GLYPH_OF_VOIDWALKER  = 56247,
 };