patchbomb: mime-encode headers and parts not containing patches Do nothing for "hg email --test" to preserve display.

mail: add methods to handle non-ascii chars - headencode, addressencode: encode headers - mimeencode: encode message parts not containing patches - new email config "charsets" Users may configure email.charsets as a list of charsets they consider appropriate for the recipients of their outgoing mails. Conversion is tried in this order: 1. us-ascii (ascii, us-ascii are removed from email.charsets if present) 2. email.charsets (if present) in order given 3. util._fallbackencoding, util._encoding, utf-8 if not already in email.charsets

mq: Allow qrefresh --silent to take parameters 'hg qrefresh --short file.txt' now adds changes made to file.txt to current patch. This builds on a patch for implementing --amend by Kirill Smelkov as discussed in issue933. FIXME: Why do mq refresh have two matchers if we only need one?