Cleaning up the message:// url injection code

Including the content transfer encoding and making more specific regex substitutions to more accurately insert the correct message:// url for the email type.
Un-flag answered emails in the "Reply to" folder

Trying something new, if a message in the "Reply to" folder is flagged as answered (something most mail clients do) then remove the flag to note the change (so it doesn't stand out as much in the mail client).