XEP-0184: send 'request' and not only 'received' messages also mark the receiving.

Hi,

the first part is fix typo for word contains receive.

The second part sends <request xmlns='urn:xmpp:receipts'/> so we got an received when client is using
XEP-0184 and not only when a client uses 'XEP-0333: Chat Markers' then when we received the 'received' message marks the timestamp with an green color. So we always know when the message arrived.
When then the 'displayed ' messages arrives then change the color of the timestamp to blue.

The problem is that i know of no who is using XEP-0333 but a lot which uses XEP-0184
and the missing indicator whether a message has arrived or not.

greets