Session handler

A middleware (PSR-15) oriented session and flash message handler for PHP.

• Blog post: https://odan.github.io/2021/01/15/slim4-session.html
• Documentation for v4: https://odan.github.io/session/v4/
• Documentation for v5: https://odan.github.io/session/v5/
• Issues: https://github.com/odan/session/issues