Core: Add wintergrasp-patch to wintergrasp_cleanup branch - resurrected from an old work-repository, now over as a branch to work on.

Original patch by socolin, cand a ton of contributors :
mathman, joda, spp, silinoron, josh, malcrom, shauren, machiavelli, click, rat, leak, tobmaps, _manuel_, the tcfr team (via socolin), and tons of others for chiming in.

NOTE: THIS IS A WORKING-BRANCH, AND _NOT_ MENT FOR PUBLIC USE OR EVEN CONSIDERED STABLE!

src/server/game/Entities/GameObject/GameObject.cpp

@@ -831,6 +831,13 @@ bool GameObject::IsDynTransport() const
     return gInfo->type == GAMEOBJECT_TYPE_MO_TRANSPORT || (gInfo->type == GAMEOBJECT_TYPE_TRANSPORT && !gInfo->transport.pause);
 }
 
+bool GameObject::IsDestructibleBuilding() const
+{
+    GameObjectTemplate const* gInfo = GetGOInfo();
+    if (!gInfo) return false;
+    return gInfo->type == GAMEOBJECT_TYPE_DESTRUCTIBLE_BUILDING;
+}
+
 Unit* GameObject::GetOwner() const
 {
     return ObjectAccessor::GetUnit(*this, GetOwnerGUID());
@@ -847,7 +854,7 @@ bool GameObject::isAlwaysVisibleFor(WorldObject const* seer) const
     if (WorldObject::isAlwaysVisibleFor(seer))
         return true;
 
-    if (IsTransport())
+    if (IsTransport() || IsDestructibleBuilding())
         return true;
 
     return false;