Support memoryview ranges in decode and encode

[i30817]

I know that some python libraries with native code have added support for this (i needs some kind of explicit reference type).

Reference: indygreg/python-zstandard#26

This can save a lot of memory depending on your buffers size. Feel free to close this if the bytes passed to the encoding and decoding functions need to operate in place on the arrays.

[samuelcolvin]

Sorry for the slow response.

I'm no expert but I believe the underlying xdelta3 c library can operate on files and therefore might be able to work with memoryviews.

Happy to discuss and accept pull requests, but I'm not actively working on this library myself right now so won't be able to implement it in the near future.