plugins TEXT-COMMANDS, XEP-0045, XEP-0048, XEP-0249:

- give a feedback instead of sending the message when the command is invalid or used in a wrong context
    - add command /join for XEP-0249

src/plugins/plugin_xep_0048.py

@@ -428,9 +428,8 @@ class XEP_0048(object):
         txt_cmd = self.host.plugins[C.TEXT_CMDS]
 
         if mess_data['type'] != "groupchat":
-            #/bookmark command does nothing if we are not on a group chat
-            log.info("Ignoring /bookmark command on a non groupchat message")
-            return True
+            self.host.plugins[C.TEXT_CMDS].feedBackWrongContext('bookmark', 'groupchat', mess_data, profile)
+            return False
 
         options = mess_data["unparsed"].strip().split()
         if options and options[0] not in ('autojoin', 'remove'):