Get ready for release 9.0.1

Change module name to Mathics3-Module-hello. Revise documentation.

Release 9.0.0 (#8)

Revise for 9.0.0 Mathics3 API.

7.0.0

• Revise for 7.0.0 Mathics3 API; we need to explicitly load builtins.
• import location of class Builtin has moved.

Father's day

Miscellaneous small changes and corrections. More comments as to what's up

A test has been added too.