Import and reuse metadata from other files

[Zekt]

Does there exist a way to import files in the metadata of a file, such that we can have global contexts with reusable metadata?

I have implemented a field in Hakyll.Web.Template.Context that checks if there is a key "import" in the metadata. If it is presented, the metadata in the given file is put in the context (by exploiting loadMetadataFile in Hakyll.Core.Provider.Metadata, which should be exported).

I will create a pull request if it is a good idea.

[Minoru]

This makes sense to me. Note that loadMetadataFile doesn't track dependencies — I guess you have a wrapper that ameliorates this? Anyway, I'd be glad to review your PR!