introduce owner concept in send_queue

In order to be able to distinguish between user-created entries and
library-internal entries, we mark each entry who it belongs to.
This allows then later to let the user manage only the queue entries
that were created by them.

Signed-off-by: Steffen Jaeckel <jaeckel-floss@eyet-services.de>

src/stanza.c

@@ -1509,7 +1509,7 @@ xmpp_stanza_t *xmpp_presence_new(xmpp_ctx_t *ctx)
  *  The error text is optional and may be NULL.
  *
  *  @param ctx a Strophe context object
- *  @param type enum of xmpp_error_type_t
+ *  @param type enum of strophe_error_type_t
  *  @param text content of a 'text'
  *
  *  @return a new Strophe stanza object