Please allow to use the pre-installed bybind11 package

[yurivict]

The pybind11 package is available for a wide variety of systems: https://repology.org/metapackage/pybind11/versions, so there is no need to download and rebuild it separately.

[sgsaenger]

Yes, but I'm new to cmake and have no clue how to reliably find the system-wide installation.
As it's header-only, i don't reckon it a pressing issue, but hints or PRs are welcome!

[yurivict]

For a header-only library it can add a cmake variable PYBIND11_HEADER_PATH variable that would use these headers.

[yurivict]

Better yet, Python binding should be its own, separate project. Systems generally have multiple versions of python installed at the same time, and the binding also needs to be independently installed at the same time for each of them. setup.py-based bindings are the best, and a way to go.

[sgsaenger]

For a header-only library it can add a cmake variable PYBIND11_HEADER_PATH variable that would use these headers.

Ah, of course. So defaulting to external/pybind11, but can be replaced with user-/maintainer-defined values. Will look into it.

Better yet, Python binding should be its own, separate project. Systems generally have multiple versions of python installed at the same time, and the binding also needs to be independently installed at the same time for each of them. setup.py-based bindings are the best, and a way to go.

The targeted python version can be choosen as for all pybind11-projects, so that's a non-issue.
I've thought about splitting it up, but there are two problems:

• especially on windows, path-mangling and package-management is not the norm, so i want to (eventually) distribute the python stuff alongside the rest. This'll lead to either circular dependencies or the need for a master-project with three subprojects.
• not the slightes clue how to correctly distribute this over PyPI, as the building would need to be performed by setup.py (no clue how to make sure that the user has all C++-dependencies) or a ton of wheels be created.
  Both are kinda too much work for too little gain, atm.

[sgsaenger]

setup.py-based installation is now implemented, together with searching for a systemwide pybind11 installation before falling back to external/pybind11.
Beginning with the next release vipster will be available on PyPI.