This reverts merge request !166

JSON should now be better so that the UI can handle it in task async
handler.

JSON should now be better so that the UI can handle it in task async
handler.

This reverts commit b3fb1a16

It introduced changes which cause issues described in
purescript-gargantext#571

This reverts commit a444cb30.

This reverts commit 22b14f56.

This reverts commit d04cf03b, reversing
changes made to e213a4bf.

It's not fully wired in, `convertQuery` for Arxiv is implemented as
`undefined`.

This commit simplifies the `ExternalAPIs` type, which is now a pure
enumeration, moving the lookup of the Pubmed key at the usage sites.
This simplified the code quite a bit, and made some otherwise-effectful
functions pure.

It doesn't add anything over just `State NgramsTableMap ()`, if not
obscuring what the single functions should actually be doing.