Merge changes Ia8f0aad4,I4631d826,I367c0d5d,I61e72625,Ifa48b631 into studio-1.4-dev

* changes:
  android/base/system/System.cpp: Make valgrind happy.
  Implements fullscreen support for the Qt emulator.
  android/skin/qt: Expandable tool window.
  android/skin/qt: Fix position of tool window.
  Add Qt-based UI backend