The signatures of all cdef class initializers in rasterio._base and
rasterio._io have changed: these method now take instance of ParsedPath
or UnparsedPath from rasterio.path and do not take strings.
New ParsedPath and UnparsedPath classes have been added to improve input
file handling and validation. The existing parse_path and vsi_path
functions have been rewritten to use these new classes and have been
moved to the new rasterio.path module. The signature of rasterio.open
has not been changed and users of Rasterio will be unaffected.
The rasterio.vfs module and its functions are being replaced by new functions
in rasterio.path.
