Merge branch 'jc/spell-id-in-both-caps-in-message-id'

Consistently spell "Message-ID" as such, not "Message-Id".

* jc/spell-id-in-both-caps-in-message-id:
  e-mail workflow: Message-ID is spelled with ID in both capital letters

diff --cc git-send-email.perl
Simple merge

diff --cc log-tree.c
Simple merge

diff --cc mailinfo.c
Simple merge

diff --cc t/t4014-format-patch.sh
Simple merge

diff --cc t/t4150-am.sh
Simple merge

diff --cc t/t9001-send-email.sh
Simple merge