Non-ASCII characters in "To" header

[krlmlr]

Example:

gmailr::create_draft(
  gmailr::mime(
    To = "Kirill Müller <krlmlr+r@mailbox.org>",
    Subject = "subject",
    body = "body"
  ),
  user_id = "me"
)

RFC 1342 (see #76 (comment)) doesn't seem to work here:

gmailr::create_draft(
  gmailr::mime(
    To = paste0(
      "=?utf-8?B?",
      base64enc::base64encode(charToRaw(enc2utf8("Kirill Müller <krlmlr+r@mailbox.org>"))),
      "?="),
    Subject = "subject",
    body = "body"
  ),
  user_id = "me"
)
## Error in gmailr_POST("drafts", user_id, class = "gmail_draft", query = list(uploadType = type),  : 
##   Gmail API error: 400
##   Invalid to header

This messes up revdep-check e-mails, might be easier to use only the e-mail address (and not the maintainer name) for now. CC @hadley.