Merge branch 'mh/imap-send-shrinkage'

Remove a lot of unused code from "git imap-send".

* mh/imap-send-shrinkage:
  imap-send.c: simplify logic in lf_to_crlf()
  imap-send.c: fold struct store into struct imap_store
  imap-send.c: remove unused field imap_store::uidvalidity
  imap-send.c: use struct imap_store instead of struct store
  imap-send.c: remove unused field imap_store::trashnc
  imap-send.c: remove namespace fields from struct imap
  imap-send.c: remove struct imap argument to parse_imap_list_l()
  imap-send.c: inline parse_imap_list() in parse_list()
  imap-send.c: remove some unused fields from struct store
  imap-send.c: remove struct message
  imap-send.c: remove struct store_conf
  iamp-send.c: remove unused struct imap_store_conf
  imap-send.c: remove struct msg_data
  imap-send.c: remove msg_data::flags, which was always zero