Allow "account" setting in [connection] to autconnect the account

closes #251

src/config/preferences.c

@@ -309,6 +309,8 @@ _get_group(preference_t pref)
         case PREF_AUTOAWAY_MODE:
         case PREF_AUTOAWAY_MESSAGE:
             return "presence";
+        case PREF_CONNECT_ACCOUNT:
+            return "connection";
         default:
             return NULL;
     }
@@ -361,6 +363,8 @@ _get_key(preference_t pref)
             return "autoaway.mode";
         case PREF_AUTOAWAY_MESSAGE:
             return "autoaway.message";
+        case PREF_CONNECT_ACCOUNT:
+            return "account";
         default:
             return NULL;
     }