"Professional CMake" book suggest the following:
"Targets should build successfully with or without compiler support for precompiled headers. It
should be considered an optimization, not a requirement. In particular, do not explicitly include a
precompile header (e.g. stdafx.h) in the source code, let CMake force-include an automatically
generated precompile header on the compiler command line instead. This is more portable across
the major compilers and is likely to be easier to maintain. It will also avoid warnings being
generated from certain code checking tools like iwyu (include what you use)."
Therefore, removed the "#include <PreCompiled.h>" from sources, also
there is no need for the "#ifdef _PreComp_" anymore
This adds isNullOrEmpty string helper that cheks if string is... well
null or empty. It is done to improve readability of the code and better
express intent.
If package.xml metadata file exists, it is scanned for FreeCAD version
compatibility before the Addon is loaded. If the Addon specifies that it is
explicitly not compatible with the current version of FreeCAD, the Addon is
not loaded.
Rather than trying to use a generic Py::Object and assigning properties
to it, use a Py::Dict object for simple data structures like Url,
Maintainer, and Author.
Update metadata standard to include subdirectory
