Allow miniz to be provided externally

[antoine-fresse]

Hello,

I have a project that already uses miniz, I had to comment out the miniz implementation in zippy and replace it with an include to miniz.h in order to not have duplicate symbols errors at link.

It would be nice to have a option in cmake to provide miniz ourselves

Thank you

[ifcquery]

Hello,

I understand your point. The thing is, I don't want to change the zippy.h header. I need zippy only for packing and unpacking ifczip files. If there is a better option than zippy, I can replace it. For now, I will keep it in mind.

[antoine-fresse]

You know I just realized that one the uses of miniz in our project was to support ifczip files before ifcplusplus supported them.

I'm not familliar with zippy, is it just a wrapper around miniz to have a c++-like API ? It's only a couple extra lines to use miniz directly, hardly seems worth it.

But anyway it's not really a big problem, as I said I just modified the zippy header in our fork to remove the miniz implementation