allow multiple outputs in ncrystal-feedstock

[tkittel]

In order to split the C++/library parts of NCrystal from the Python layer, the ncrystal-feedstock needs to be modified to use multiple outputs. So before there was just an "ncrystal" package, but in the future there will be at least "ncrystal-core", "ncrystal-python", and "ncrystal" packages, where the last will be a metapackage depending on the rest and ensuring synchronisation of versions. In the future the ncrystal-core itself might be split further (into libs, headers, data files), but that is not going to happen in the short term.

I am the maintainer of the ncrystal-feedstock, so I count myself as having been pinged :-)

• I want to add a package output to a feedstock:
  • Pinged the relevant feedstock team(s)
  • Added a small description of why the output is being added.

[h-vetinari]

Why not call the C++ library libncrystal?

[tkittel]

@h-vetinari mostly because it is not 100% just the lib, but more importantly to follow 1-to-1 the naming of the corresponding pypi packages.