[Paraview] ParaView and Qt 5

[Utkarsh Ayachit]

Folks,

With upcoming release (5.3), we plan to move to using Qt 5 by default.
Qt 5 has been out since 2012 and it is well supported on modern
platforms. ParaView will continue to build with Qt 4 until further
notice, but we highly recommend custom application developers and
plugin developers to move to Qt 5 at the earliest since active
development and testing for ParaView will happen with Qt 5.

Changes [1] that landed in master earlier today update ParaView to now
use QOpenGLWidget for rendering which creates a frame buffer object to
do all the rendering in. If you have custom mapper or rendering code
that assumed it was rendering to the default onscreen frame buffer, it
will not work correctly and will need to be updated. Please use the
mailing, if you encounter any such issues. For everything else, the
changes should be fairly transparent except in exceptions documented
here [2].

In the upcoming weeks, we will update the superbuild and dashboards to
build and test using Qt 5.

Thanks,
Utkarsh


[1] https://gitlab.kitware.com/paraview/paraview/merge_requests/1279
[2] https://gitlab.kitware.com/paraview/paraview/blob/master/Utilities/Doxygen/pages/MajorAPIChanges.md#changes-in-53