Resolve "Rewrite spameater from scratch"

Closes #42 (closed) ; Relates to #27 (closed) #29 (closed) #30 (closed) #41

Unit tests on the erine_email Python package ✅

$ python3-coverage run test.py 
...................
----------------------------------------------------------------------
Ran 19 tests in 0.054s

OK

100% code coverage on the erine_email Python package ✅

$ python3-coverage report
Name                              Stmts   Miss  Cover
-----------------------------------------------------
erine_email/__init__.py              20      0   100%
erine_email/classic.py               26      0   100%
erine_email/classic_reserved.py      33      0   100%
erine_email/common.py                 5      0   100%
erine_email/firstshot.py             39      0   100%
erine_email/generic.py               55      0   100%
erine_email/reply.py                 52      0   100%
erine_email/reserved.py              26      0   100%
test.py                             153      0   100%
-----------------------------------------------------
TOTAL                               409      0   100%

pyflakes3 ✅

$ pyflakes3 python_pkg/files/test.py python_pkg/files/erine_email/*.py

Black ✅

$ black --line-length=120 python_pkg/files/test.py python_pkg/files/erine_email/*.py
All done! ✨ 🍰 ✨
9 files left unchanged.

Traviata ✅ (Alice uses YMail, Bob GMail).