Suppress warnings

This removes warnings causes by the module's own code. There are still many warnings emitted by the rest of the Dune framework. There are two notable remaining warning types from this code:
 - Deprecation warnings have not been suppressed, as they point us to work we have to do eventually.
 - The function removeUnusedNodes() is unused (at its only call site the call is commented out), I am unsure if this function remains useful, so I have not deleted it yet.