Updated QtTesting to use Qt5

QtTesting should use user selected Qt version
Change-Id: I22337268e9864b5fe2153309f6844cdf3ab4e4b3
WIP: Restore Qt4 and enable option to build against Qt5

Change-Id: If3cb97ff798b22a5fb4e89c0be948ca6b65ee1d1
Fixed examples to use Qt4 or Qt5 depending on user preference

Change-Id: Ieb302552284d52ed61a4f552ec4526c176392af8
Fixed ParaView macros to use both Qt4 and Qt5

Change-Id: I595069f00809082e30770e0c3e2dcd14ef8f69ae
Include ParaViewQt5.cmake instead of doing find_package(Qt5)

Change-Id: Ia356394db4c876eeeccc42845af5156749e97479
Reverted macros to use both Qt4 and Qt5

Change-Id: Ibf7b9d492b170232d3f5649ac6a0a14f4da95dd4
QHeaderView maintain both Qt4 and Qt5 changes

Change-Id: Ie6752fb7d36af8431ebb6ea58928ed31ef776de5
Make both QInstallMessageHandler and QInstallMsgHandler available

Change-Id: I0a044f700ce3978971508521aad2dd8e1fa17397
Add Qt5Core to the list of imported modules

Change-Id: Ibb51a044fe0b912a23cbcefc34e2eaeb2a72baa2
Plugins use either Qt4 or Qt5

Change-Id: If9915400df6917e07f700a7fc0152b4c5b9981a7
Use Qt4 or Qt5 plugin architecture

Change-Id: Ifca120a2936b2df7b1844afaa0b61d71c3ce245c
Import Qt5Widgets module at the top level

This ensures all the required Qt5 variables can be found.
For example, just importing Qt5Core does not help find QT_UIC_EXECUTABLE using
the macro "get_target_property(QT_UIC_EXECUTABLE Qt5::uic LOCATION)". This must
be a Qt5 bug.

Change-Id: Ie6f4a708682ad8cf2391d218c193d8127e4c44f7