Display virtual accounts at the end

Fix a bug in LonkOrUnlinkOperation (when year was not previously loaded)
Translate categories in PreferencesPanel

src/model/User.cpp

@@ -170,6 +170,12 @@ void User::LinkOrUnlinkOperation(Operation& op)
     std::vector<Operation>::iterator it;
     Account account, account2;
 
+    if (!_operations[op.year])
+	_db->LoadYear(this, op.year);
+
+    if (!_operations[op.year])
+	return;
+
     // Not Linked
     if (!op.transfert.Length())
     {