Zenodo release and conda-forge

[tpeulen]

The source code is now tight to Zenodo releases. However, the Zenodo release does not do a git clone --submodule.

Hence, due to the dependency on thirdparty submodules LabelLib cannot be built with the Zenodo release alone.

I know, this is not very elegant, however, to make it possible to build LabelLib using the Zenodo release alone and to address the issue that conda-forge wants releases to be build from tarballs as opposed to git repositories, we should consider coping the dependencies instead of using submodules.

This would solve issues with conda-forge and zenodo alike.

For the next release we could/should link labellib to Zenodo (see: link). This way, LabelLib gets a DOI and could be cited.

Originally posted by @tpeulen in #11 (comment)

[mdimura]

Since thirdparty/Eigen and thirdparty/pybind11 are only used as fallback, it should be sufficient to explicitly copy pcg-cpp, which we totally could do. And for conda-forge we could use automatic github tarballs, which are generated for any github release.

[mdimura]

The issue can be discussed in #19

[tpeulen]

I just submitted labellib to conda-forge. There was in issue with the windows build. Hence, I skip the Windows build for now. see conda-forge/staged-recipes#15497