[grid.provider]
* removed dynamic id()
* updated static_id()
[grid.provider.cube] let default_config() return a ConfigTree
[functions.interfaces] minor update to visualize()
[grid.provider] updated exceptions and ids
[grid.boundaryinfo] major renaming
* GridboundaryInterface -> Grid::BoundaryInfoInterface
* GridboundaryFoo -> Grid::BoundaryInfos::Foo