Expose fastNLO converter to Python/Rust/...

[alecandido]

• move the current fastnlo module from the CLI to the main crate
• bind in the Python interface

[cschwan]

I'll take care of the first part, and you can write bindings afterwards!

[cschwan]

I tried doing this and unfortunately didn't succeed, probably due to a linking-order problem with LHAPDF: it seems to matter whether I link LHAPDF first and fastNLO second, because the latter depends on the former and the CLI depends on both. I think that this problem can't be solved with cargo, so this Issue probably has to be postponed for a while.

[alecandido]

Sad, but fine.

In any case, it is not a major issue at the moment: it was mainly needed to start writing "pinecards" for conversion, in order to have consistent metadata, include versions and so on.
But pinecards (I'd really like to call them seeds :D) are going to be reworked anyhow (at least a bit), after the new commondata will be available.

In the meantime, if we'll generate our own grids, we might stop doing systematic conversion. Let's worry afterwards.

[felixhekhorn]

For writing the APPL conversion pinecards we need to run the "CLI" (meaning the appl2pine command) in any case (for the moment) so we can even call the PineAPPL CLI there ...

In any case NNPDF/pinefarm#3 is not liked to CommonData ...

[alecandido]

I'd still assign low priority to this task: we already converted all the grids we needed, it's non-blocking for anything.
It's a refinement we want, but still a refinement.