expose empty server functionality and test it (also introducing a new DC_EVENT_IMAP_FOLDER_EMPTIED event)

python/src/deltachat/account.py

@@ -135,6 +135,17 @@ class Account(object):
         if not self.is_configured():
             raise ValueError("need to configure first")
 
+    def empty_server_folders(self, inbox=False, mvbox=False):
+        """ empty server folders. """
+        flags = 0
+        if inbox:
+            flags |= const.DC_EMPTY_INBOX
+        if mvbox:
+            flags |= const.DC_EMPTY_MVBOX
+        if not flags:
+            raise ValueError("no flags set")
+        lib.dc_empty_server(self._dc_context, flags)
+
     def get_infostring(self):
         """ return info of the configured account. """
         self.check_is_configured()