Core/Units:

- Implement UNIT_FIELD_HOVERHEIGHT (requires DB data). This field, sent in update object packet, will determine the height at which a creature hovers if it has movementflag_hover applied. Note that hovering will now update the server-sided z-coordinate by the value of this field, and that all subsequent positional updates to the client will need to send z coordinate MINUS the hover height offset, or the hoverheight will be visually doubled client side.
- Correct our usage of movementflag_flying, movementflag_can_fly, movementflag_hover and movementflag_disable_gravity (previously levitate), and how they relate to InhabitType in the database. This fixes "flying creatures on steroids" bug (wings flapping too fast), and potentially a lot of visual issues in AI scripts. Note that a lot of scripts still set wrong movementflags, these need to be fixed on a case by case basis.
- Send correct packets for SPELL_AURA_FEATHER_FALL, SPELL_AURA_WATER_WALK and SPELL_AURA_HOVER apply/unapply.
- Send correct packet contents for movement update in Unit::SetSpeed.
- Misc. cleanup in affected scripts.

src/server/scripts/Kalimdor/silithus.cpp

@@ -576,7 +576,7 @@ public:
                         break;
                     case 10:
                         Merithra->HandleEmoteCommand(EMOTE_ONESHOT_LIFTOFF);
-                        Merithra->SetLevitate(true);
+                        Merithra->SetDisableGravity(true);
                         Merithra->GetMotionMaster()->MoveCharge(-8065, 1530, 6.61f, 3);
                         break;
                     case 11:
@@ -603,7 +603,7 @@ public:
                         break;
                     case 18:
                         Arygos->HandleEmoteCommand(EMOTE_ONESHOT_LIFTOFF);
-                        Arygos->SetLevitate(true);
+                        Arygos->SetDisableGravity(true);
                         Arygos->GetMotionMaster()->MoveCharge(-8065, 1530, 6.61f, 42);
                         break;
                     case 19:
@@ -630,7 +630,7 @@ public:
                         break;
                     case 26:
                         Caelestrasz->HandleEmoteCommand(254);
-                        Caelestrasz->SetLevitate(true);
+                        Caelestrasz->SetDisableGravity(true);
                         Caelestrasz->GetMotionMaster()->MoveCharge(-8065, 1530, 7.61f, 4);
                         break;
                     case 27:
@@ -769,7 +769,7 @@ public:
                         break;
                     case 63:
                         me->HandleEmoteCommand(254);
-                        me->SetLevitate(true);
+                        me->SetDisableGravity(true);
                         break;
                     case 64:
                         me->GetMotionMaster()->MoveCharge(-8000, 1400, 150, 9);