Widgets: Set qt_button_down for each press.

Do not rely on release events.

Task-number: QTBUG-31333
Change-Id: I09a056fed8892715c04ca78a42ae191e5a9a3b42
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Use BSD licensing for QtOpenGLExtensions instead of LGPL

BSD licensing should be used for QtOpenGLExtensions instead of LGPL as
it is a static library that is linked into applications. Using LGPL
would impose additional requirements for application developers to
provide object files to end users to be able to relink the application
with a modified or updated QtOpenGLExtensions static library.

Task-number: QTBUG-29918
Change-Id: I0bb80f8ba5158be0a71fe4c5e1c37787ce21337d
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>