Add missing Q_REVISION

This invokable method is new in Qt 5.1/QtQuick 2.1

Change-Id: I7d0e332b52a815ac0722e39db68ef1f190534a57
Reviewed-by: Liang Qi <liang.qi@digia.com>
QQmlPlatform: rename "mac" to "osx"

Change-Id: Ie458690b8008b211785cf9dcc0312a7e25c84f6b
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>
Update 5.1.0 changelog and what's new

All the new features should now be listed in those two documents

Change-Id: Ifa17581bf589f3a18b602f8a1d10683a5e48c70d
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>
Merge remote-tracking branch 'origin/release' into stable

Change-Id: I6e060496b8c252fb4e2d5d2d40ae16bf950e2ec4
Merge "Merge remote-tracking branch 'origin/release' into stable" into refs/staging/stable