-Improved group loading from the database:

--TShock will now attempt to load any available valid group data even if there are invalid records and will also report proper errors / warnings.
--"superadmin" is now a reserved group name.
--Groups with parents causing infinite parent loops, invaild parents, or parenting theirselfes will have their parent group reset.
--Double definitions of groups with the same name are no longer allowed.
--Group instances are now tried to be preserved instead of being recreated during a reload of the group data.

-Added command "/group parent" to get and set the parent of groups.
-REST Endpoint "/v2/groups/create" will no longer allow creating groups having theirselfes as parent.
-REST Endpoint "/v2/groups/update" will no longer allow setting a group's parent to theirself or setting a parent group resulting in an infinite parent loop.
-This commit should fix #482.

TShockAPI/Group.cs

@@ -204,7 +204,7 @@ namespace TShockAPI
                     return true;
                 if (traversed.Contains(cur))
                 {
-                    throw new Exception("Infinite group parenting ({0})".SFormat(cur.Name));
+                    throw new InvalidOperationException("Infinite group parenting ({0})".SFormat(cur.Name));
                 }
                 traversed.Add(cur);
                 cur = cur.Parent;
@@ -270,6 +270,26 @@ namespace TShockAPI
 				return;
 			}
 			permissions.Remove(permission);
+		}
+
+		/// <summary>
+    /// Assigns all fields of this instance to another.
+    /// </summary>
+    /// <param name="otherGroup">The other instance.</param>
+		public void AssignTo(Group otherGroup)
+		{
+			otherGroup.Name = Name;
+			otherGroup.Parent = Parent;
+			otherGroup.Prefix = Prefix;
+			otherGroup.Suffix = Suffix;
+			otherGroup.R = R;
+			otherGroup.G = G;
+			otherGroup.B = B;
+			otherGroup.Permissions = Permissions;
+		}
+
+		public override string ToString() {
+			return this.Name;
 		}
 	}