macros: Merge generate_element_with_children!() into generate_element!().

src/muc/muc.rs

@@ -5,7 +5,7 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-generate_element_with_children!(
+generate_element!(
     Muc, "x", MUC, children: [
         password: Option<String> = ("password", MUC) => String
     ]

src/muc/user.rs

@@ -142,7 +142,7 @@ generate_attribute!(Role, "role", {
     None => "none",
 }, Default = None);
 
-generate_element_with_children!(
+generate_element!(
     Item, "item", MUC_USER, attributes: [
         affiliation: Affiliation = "affiliation" => required,
         jid: Option<Jid> = "jid" => optional,
@@ -155,7 +155,7 @@ generate_element_with_children!(
     ]
 );
 
-generate_element_with_children!(
+generate_element!(
     MucUser, "x", MUC_USER, children: [
         status: Vec<Status> = ("status", MUC_USER) => Status,
         items: Vec<Item> = ("item", MUC_USER) => Item