Revert "Handle new QtTraceMsg type, fix warnings about unhandled enumeration value."

This reverts commit bf49d9f0d41c3be802dbdd2c23dfe7c5fd86f4b0.
QtTraceMsg was removed from QtCore for the moment, too.

Change-Id: I1d6aaacf5e363f81272da4fbb0a4ff12337dd677
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
QAbstractXmlNodeModel: avoid undefined behavior

In 409655f3451815930b70a71baa175ab9f34467ed, the C-style cast was replaced
by pointer arithmetic:
  char *null = 0;
  return null + offset;

Says the standard (5.7 [expr.add]/5):
   When an expression that has integral type is added to or subtracted from
   a pointer, [...] If both the pointer operand and the result point to
   elements of the same array object, or one past the last element of the
   array object, the evaluation shall not produce an overflow; otherwise,
   the behavior is undefined.
Iow: the above code has undefined behaviour.

Fix by going back to the casting version, but using a C++
reinterpret_cast instead of a C-style one.

Task-number: QTBUG-32735
Change-Id: Ia774491b13b1c52089daf63a7921b163fc93abce
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Doc: Updated url variable in qdocconf files.

In 5.2, the HTML output is in a flatter structure and when they are
hosted in qt-project.org/doc, the documentation will be found at
http://qt-project.org/doc/qt-$QT_VER

The url variable is used by projects outside of Qt 5 which need
to link to Qt 5 documentation, such as Qt Creator.

Task-number: QTBUG-34584
Change-Id: I7f989870b311e101ed4de85f3139f010012cfd71
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Merge remote-tracking branch 'origin/stable' into dev

Change-Id: Ib71b7f22be969dae2e1f4bfc20bc8d5478679e5c