WIP: Remove c++98 support, Qt4 and VTK7. Last commit also removes Qt5.5 support.

COMP: Remove C++98 support

Remove logic involving checks for CMAKE_CXX_STANDARD=98

COMP: Remove support for Qt4 and VTK7

Slicer_REQUIRED_QT_VERSION is at least 5.0.0

This allows to remove a lot of logic in form of #ifdef involving checking for QT_VERSION lesser than 5.0.0

COMP: Remove C++98 support

Remove logic involving checks for CMAKE_CXX_STANDARD=98

This branch integrates work done in #1060 but with new CMake

Co-authored-by: Hans Johnson hans-johnson@uiowa.edu Co-authored-by: Pablo Hernandez-Cerdan pablo.hernandez.cerdan@outlook.com