With cache off, we use different loader to allow for page, string, etc
queries directly to the API.

Remove Gargantext.Utils.Seq: if we need it, it should be one directly implemented using the underlying tree

Instead of removing them from the list, just set the 'hidden' property
accordingly.

This reverts commit ed096142.

This is updated on the backend when ngrams are updated.

Instead of modifying state (which causes rerendering and removal of
current selection), we use refs.

This has the drawback of delayed popup showing, unfortunately (this
happens when backend send the periodic PUT message).

Also, some fixes to react component errors.