vmime::net::imap::IMAPFolder::getMessageCount() doesn't update its value once IMAPFolder instance created

[cat-cat]

vmime::net::imap::IMAPFolder::getMessageCount() doesn't update its return value once IMAPFolder instance created.

How to reproduce:

1. Request IMAPFolder from IMAPStore, call getMessageCount(), remember return value
2. Receive new letter (via web interface) in the folder for which you created IMAPFolder instance in step above.
3. Call getMessageCount() on IMAPFolder instance created in step 1, check return value.

Expected result - return value from call to getMessageCount() in step 3 should be higher then return value from call in step 1.
Actual result - return value from call to getMessageCount() in step 3 is equal to return value from call in step 1.

Checked with Gmail account.