Get parse_basic.py running against lots of MIME

Also, in the process: add nice long repeating-underscore headers to the
top of each command in "session.txt"; remove silly "enjoy it!" messages
from each sample message; make sure that "parse_basic.py" works against
all three MIME sample messages; set LANG to UTF-8 so that we do not die
with an exception when Michael Müller is mentioned in a header.
Tell ".gitignore" that we renamed "session_out.txt"