"git send-email" learned to handle more forms of sendmail style
aliases file.
* es/send-email-sendmail-alias:
send-email: further warn about unsupported sendmail aliases features
t9001: add sendmail aliases line continuation tests
t9001: refactor sendmail aliases test infrastructure
send-email: implement sendmail aliases line continuation support
send-email: simplify sendmail aliases comment and blank line recognizer
send-email: refactor sendmail aliases parser
send-email: fix style: cuddle 'elsif' and 'else' with closing brace
send-email: drop noise comments which merely repeat what code says
send-email: visually distinguish sendmail aliases parser warnings
send-email: further document missing sendmail aliases functionality