crond: add handling of "MAILTO=user" lines

crond: add handling of "MAILTO=user" lines
sendmail: handle a case when the whole mail comes from stdin
(and no separate sender/subj is provided)
both by dronnikov AT gmail.com

function                                             old     new   delta
sendgetmail_main                                    1509    1674    +165
SynchronizeFile                                      671     767     +96
packed_usage                                       24054   24088     +34
crond_main                                          1404    1420     +16
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(add/remove: 0/0 grow/shrink: 4/0 up/down: 311/0)             Total: 311 bytes