Add version number to facelift

[derived-coder]

I want to create a conan recipe for facelift and therefore I need a version number in order to say, this recipe is for version x.y.z ? Something like this: facelift/1.0.0@conan/stable You cannot use the git hash for that. It is not human readable anyway and I cannot compare it with a bigger and smaller version.

Unfortunately it seems to be that facelift doesn't have a version number. Which is kinda strange. I propose to add a git tag from now and also that the version number is added as variable in cmake and from this automatically a header file created. So I can compare versions at compile time too. I can make a PR for this. But I want to ask before doing this. I guess I am not the only one who needs this "feature".