Use Packagemanager for external libs

[3dJan]

Building OpenVDB and its dependencies can be a time consuming chore. Doing that with a package manager like vcpkg would be much easier, is more portable than a binary zip and upgrading the libs is much more convenient. See howto.

[ryein]

vcpkg would be a good to switch to. when i originally built this in 2018 it was a bit buggy. i had run into issues when building the static libs with vcpkg. i was trying to build static in order to minimize the dll files needed when packaging for grasshopper and food4rhino.

my main concern in my prior reply was how would i package this for mac on food4rhino. that is how most people are accessing the library. vcpkg would be a better system for github but i also need to be able to build the dll and gha files for both mac and windows to upload to food4rhino.

[ryein]

updated in latest commit to use vcpkg