Deprecate mapper.update and the gridview-specific mappers

This MR attempts to fix #129 (closed)

• deprecate mapper.update() which is replaced by mapper.update(gridView)
• the Mapper base class now forwards to asImp().update(gridView) only if this member function exists in the implementation and otherwise forwards to update() which throws a deprecation warning.
• deprecate LeafMultipleCodimMultipleGeomTypeMapper,LevelMultipleCodimMultipleGeomTypeMapper,LeafSingleCodimSingleGeomTypeMapper,LevelSingleCodimSingleGeomTypeMapper because they are obsolete
• update the tests to use the new update function
• use the base class in the tests to test the common CRTP interface.
• make corresponding change in the Python bindings