implement http_shell

[GarryMorrison]

No description provided.

[GarryMorrison]

OK. My code is butt ugly, but it implements some of the basics.
We can do things like:

sa: load bottles-of-beer.sw
sa: sing

sa: load family.sw
sa: graph

sa: load temperature-conversion.sw
sa: load print-temperature-table.sw

sa: load fred-sam-friends.sw
sa: table[name, friends] split |Fred Sam>

sa: files
sa: dump
sa: dump multi
sa: history

[GarryMorrison]

Invoke using:

python3 http_shell.py

It listens on localhost, port 8080.