Gemcall Now Supports Streaming and More

Big changes to my CLI gemini client gemcall in the past few days!

• Replaced getopt with argparse. I think Solene initially suggested argparse, but I somehow got it into my head that it wasn't part of the standard library. That mistake is now amended.
• The client can now be used as a lib. It provides the function gemcall.request, which returns a gemcall.Response object. This has everything you need to build a more feature-full client or browser around.
• It supports streaming! It will output data as it comes in, instead of waiting for everything to download first.
• The response code and meta line are now printed to stderr instead of stdout, neatly separated from the response body.
• Speaking of which, you can now choose to omit the header output -- or ONLY print the header.

This is a big thing. After some battle testing I intend to read up on how to make this available to pip install.

Please let me know if you have questions or find issues.

-- CC0 ew0k, 2021-07-11