Xml does not support control characters (even if encoded), thus
QXmlStreamWriter does not encode them, and QXmlStreamReader gives an
error with them.
Thus outputting a control char would stop the application.
Now we send them with a special tag and decode them.
Note that the Output pane does some emulation of terminal behavior
when receiving them.
Sending app output as block because otherwise the stange logic
within the OutputPane inserts spurious newlines (a string not
containing a newline always gets a newline prepended) .

Task-number: QTCREATORBUG-11219
Change-Id: I3557ffbb23ca2ea4eec9a97335a95580c9c4482b
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>