[Qt5] rqt_bag: Scrolling on timeline view causes crash

[mjcarroll]

Using 16.04 x64, QT 5.5.1, Kinetic:

Loading a bag in rqt_bag then using the mouse scroll wheel over the timeline causes the crash:

Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_bag/bag_timeline.py", line 496, in on_mousewheel
    self._timeline_frame.on_mousewheel(event)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_bag/timeline_frame.py", line 1090, in on_mousewheel
    dz = event.delta() / 120.0
AttributeError: 'QWheelEvent' object has no attribute 'delta'

Looking at this: http://doc.qt.io/qt-5/qwheelevent.html#angleDelta, it looks like delta has been deprecated in favor of angleDelta and pixelDelta.

[dirk-thomas]

Duplicate of #376. The fix is already available in the latest release of this package: version 0.4.1.

[mjcarroll]

Thanks and apologies, I even searched (poorly)!