Prepare arguments for addDrawToolbar or addPmToolbar
processOpts(fun, args)An object suitable for passing in as the supplied argument
to either leaflet.extras::addDrawToolbar or
leafpm::addPmToolbar.
Function used by editor package (leafpm or leaflet.extras) to set defaults
Either a (possibly nested) list of named options of
the form suitable for passage to fun or (if the chosen
editor is "leaflet.extras") FALSE.