signature() deprecated in Qt5.

Use methodSignature() in Qt5.
Qt's sdk doesn't define unicode.
Qt::escape moved to QString::toHtmlEscaped in Qt 5
Don't keep qt4 support.
Qt5's connectNotify() has been modified.

In Qt5 connectNotify() receive a QMetaMethod instead of a char pointer. fromSignal() takes a signal as an argument and returns the corresponding QMetaMethod.
reset is deprecated since Qt 5.0
No more posF in Qt 5; use the new localPos
QKeySequence's int operator is deprecated

operator int returns the first key in the sequence, so just use that
one directly.
QTreeView::dataChanged's signature changed.
Logging changed in Qt 5; use QtMessageHandler
Remove if defs.
qVariantCanConvert is deprecated
setAlphaChannel is deprecated in Qt 5.

With the default CompositionMode this should work too.
Qt5 changed the location of QWebView.
setAcceptsHoverEvents is deprecated in Qt 5.

setAcceptsHoverEvents has been around since 4.4
qVariantValue is deprecated in Qt 5.0
Webkit changed location and scale() is gone.

Webkit's include location changed and scale() is replaced by transform().
setResizeMode() is renamed to setSectionResizeMode() in Qt5.
Prevent unused-but-set warnings ifndef QT_NO_DEBUG
Unnecessary forward declaration of CoreSession.