Fully remove Send Later headers that are wrapped by IMAP servers
Fully remove Send Later headers that are wrapped by IMAP servers

Send Later inserts several headers into scheduled messages and removes
those headers when delivering the scheduled messages. When Send Later
inserts these headers, their contents are all on a single line in the
message header, and the logic in Send Later for removing the headers
previously assumed that the contents would _remain_ on a single line.
However, some IMAP servers "kindly" wrap headers when messages are
saved into an IMAP server. As a result, some Send Later headers were
being wrapped, and then Send Later removed those headers incompletely
because it left behind the wrapped text. The code has now been fixed
to remove the wrapped text as well.

jikamens/send-later,jikamens/send-later,jikamens/send-later,jikamens/send-later