Remove conversion of svg to html for generic usage.

ihaskell-widgets: Port to vinyl-0.9

Fixes #998.

Change program type from ByteString to String and remove RankDir because
that can be configured in the input.

Remove duplicate module `IHaskellPrelude`.

remove module from `main`, and promote from `other-modules` to
`exported-modules` in `library`.

Fixes #971.

Implement update_display_data message

This commit adds new message update_dispaly_data and updates
display_data message to add optional transient field which
is in turn used by update_display_data

Fix protocol communication with jupyter-lab.

Moves package from using jupyter-notebook to the jupyter-lab.
Both backends can still be used using: ihaskell-notebook and
ihaskell-lab respectively.