Use Q_DECL_RELAXED_CONSTEXPR in QFlags

Change-Id: I91073f4bb71e554402fc13cbd0e9ba5b5b95bce0
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
QIdentityProxyModel: remove slow bounds-checking, for more performance

If we're called out of bounds, sourceModel()->index() will take care of
returning an invalid model index anyway. So calling rowCount+columnCount
every time index() is called can be avoided. These calls can be particularly
slow when sitting on top of a stack of proxymodels. And index() itself is called
very often, i.e. when a proxymodel on top of us is used by a delegate
which calls data() for many different roles.

Change-Id: I45ad6249ea6c6c719a28d25a03b6e5003f4e49ee
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>
Add QMetaType::type(QByteArray) function

QMetaType::type(const char *) requires that the string argument is
0-terminated. This new overload makes it possible to query the type
of a string with an explicit length.

In particular, QByteArrays constructed by QByteArray::fromRawData(),
for example from a substring of a normalized method signature (the
"int" part of "mySlot(int"), can now be queried without making a copy
of the string.

Also, Qt5 meta-objects represent type names as QByteArray literals,
which can be fed directly to this new QMetaType::type() overload (no
need to call strlen).

Change-Id: I60d35aa6bdc0f77e0997f98b0e30e12fd3d5e100
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Implement QTableWidget/QListWidget::mimeData()

For some reasons lost in history, those methods simply ignore
the list of items passed to them, and always return NULL.
Of course, that's totally broken. Fix that by doing the same thing
that the respective (hidden) models did when calling mimeData().

Surprisingly enough, QTreeWidget has a proper implementation.

Task-number: QTBUG-25900
Change-Id: I99ca7b4d4f87f096fd9ff0b0cb4e58282aa9c26e
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: David Faure <david.faure@kdab.com>
Add QKeySequence::Backspace

Handle it in QWidgetTextControl. Add Meta(ctrl) + H
key sequence binding on Mac.

Task-number: QTBUG-32837
Change-Id: Ib1cbb2ce2e20350b4d8c72bd320dff27c1467f2b
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Liang Qi <liang.qi@theqtcompany.com>