timestamp problem about QXmppMessage

[LightZam]

There is a problem for me using QXmppMessage
the mthod QXmppMessage::parse, will using XEP-0091: Legacy Delayed Delivery in the end.

because the order of code, legacy will replace XEP-0203 : Delayed Delivery's value

below code is the xml example, i have no chance to get timestamp with millisecond because of d->stamp will use the legacy delayed delivery.

XEP-0091 is not recommended now, can the XEP-0203 parse code move to below XEP-0091, then it will
replace XEP-0091's timestamp if there is XEP-203

if you agree with this, maybe i can make a pull request

<message type="groupchat" from="crd_cii@groupchat.im.gss.com.tw" to="zam_huang@im.gss.com.tw/QXmpp">
    <subject>CRD_CII</subject>
    <delay xmlns="urn:xmpp:delay" stamp="2014-11-13T06:57:41.509Z" from="crd_cii@groupchat.im.gss.com.tw"/>
    <x xmlns="jabber:x:delay" stamp="20141113T06:57:41" from="crd_cii@groupchat.im.gss.com.tw"/>
</message>

[jlaine]

OK, this is a valid point, I agree with using the most recent standard foremost, and only falling back to XEP-0091

[jlaine]

Closed in #53