Review Fabio Rossi's contribution, fetchmail-mda-fork.*, polish and merge.

Return PS_ERROR, not PS_SYNTAX, on failures for preconnect/postconnect.
Credit to Gene Heskett, 2012-07-31, fetchmail-users@ list.

support SHA1 (and possibly other algorithm) finger prints
(grarpamp, fetchmail-users 2012-06-23)

add a "send test mail" mode, see message by Stanley Dziegiel
<stanley@stronglg.demon.co.uk> in fetchmail-users, 2012-05-30

fix NUL generation (see 6.3.21 release) and possibly string length
handling

review retrieveerrorsemantic contribution to avoid mail loss (cf. POP3
LAST)

clean up KPOP, SSL options

fix versions in features.html (6.4 vs. 7.0)

update README

check for other 6.2/6.3-specific documentation

merge libpwmd updates

fix versions 7.0/6.4/6.3.20 in fetchmail.man, want 7.0 for this release,
and 8.0 for C++

SSL fixes:
- write .man documentation, adjust FAQ (check diffs for what needs to be
  documented)
- debug sslcertck default (gets disabled somehow)

Debian #632479 - doesn't accept -f and --pidfile options when waking up
BG daemon (watch out for idfile though!)

- debug mode fix: one switch to kill running daemon and enable -Nvvv -d0
  --nosyslog options

- write email to flat files? (variant of bsmtp)

- probably 8.0 stuff: IMAP sink

- remove bouncemail feature?

- validate addresses to avoid invalid address issues
    + consider if a bad-header interaction is desired