Log Message:
neomutt: update to 20180512.

2018-05-12  Richard Russon  <rich@flatcap.org>
* Features
  - echo command
  - Add $browser_abbreviate_mailboxes
  - Add ~M pattern to match mime Content-Types
  - Add support for multipart/multilingual emails
  - Jump to a collapsed email
  - Add support for idn2 (IDNA2008)
* Bug Fixes
  - Let mutt_ch_choose report conversion failure
  - minor IMAP string handling fixes
* Translations
  - Chinese (Simplified) (100%)
  - Czech (100%)
  - German (100%)
  - Lithuanian (62%)
  - Portuguese (Brazil) (100%)
* Coverity defects
  - match prototypes to their functions
  - make logic clearer
  - reduce scope of variables
  - fix coverity defects
* Docs
  - development: analysis
  - development: easy tasks
  - development: roadmap
* Code
  - start refactoring libconn
  - split out progress functions
  - split out window functions
  - split out terminal setting
  - convert MyVars to use TAILQ
  - split mutt_file_{lock,unlock}
  - Move IDN version string to mutt/idna.c
  - refactor: init_locale()
  - Eliminate static variable in mutt_file_dirname
* Tidy
  - test int functions against 0
  - rename lots of constants
  - rename lots of functions
  - sort lots of fields/definitions
* Upstream
  - Increase account.user/login size to 128
  - Fix comparison of flags with multiple bits set
  - Change mutt_error call in mutt_gpgme_set_sender() to dprint
  - Improve the error message when a signature is missing
  - pager specific "show incoming mailboxes list" macro
  - Improve gss debug printing of status_string
  - Remove trailing null count from gss_buffer_desc.length field
  - Add a comment in auth_gss about RFCs and null-termination
  - Change prompt string for $crypt_verify_sig