* Use horizontalAdvance
* Remove unused code
* Hide some warnings from Qt code
* Remove message for _SILENCE_TR1_NAMESPACE_DEPRECATION_WARNING
* Use CMP0077 NEW
* Move roff libraries to folder Thirdparty
* avoid operator()==
* Remove cmake_minimum_required and set version to 3.15
Move Add and Delete command features there.
Implement generic Toggle Commands.
Make library an cmake "OBJECT" library to allow "registering by static initialization".
Add the concept of CurrentContextMenuTargetWidget into CmdFeatureManager to support the toggle commands.
Updated test application to use the new commands