SWI-Prolog implementation of the todo-backend API

These files implement Todo-Backend, a shared example to showcase backend tech stacks in SWI-Prolog version 7. The implementation uses the Prolog database with file backup to provide persistency.

Roadmap:

• run.pl allows for loading and starting the server.
• daemon.pl As run.pl, but supports Unix service interaction. Edit the #! line and run ./daemon.pl --help.
• server.pl provides the webserver intialization.
• todo.pl is the real server. It is extensively documented to help Prolog novices understand the code.

Notes

• The implementation relies heavily on SWI-Prolog's web server infrastructure. I have also used SWI-Prolog version 7 extensions that are intended to make Prolog code look less alien by providing dicts and strings.

• Requires SWI-Prolog >= 7.1.21