update UPDATING with 1.5.22 release date
remove <stdbool.h> and use "1" instead of "true".  closes #3657

see #3642 for the change that caused this bug.
add note about use of ! ~Q in send-hook when paired with reply-hook.
Terminal status line support, based on the xterm title patch.

Christoph Berg took the xterm title patch from the mutt mailing list and
maintained it for Debian:
* Changes made:
  - 2007-01-27 myon: using %P caused a segfault, updated status.c to catch
    menu==NULL.
  - 2007-02-20 myon: make the note about the xterm_set_titles defaults a
    comment.
  - 2008-08-02 myon: move set_xterm_* prototypes into the proper header file
    (cleaner code, no functional change, evades conflict with sidebar patch)

This update reworks the Debian version as generic support for tsl/fsl
terminfo capability.  It no longer depends on a static list of supported
terminal types, although it will use default support for these terminal
types *if* they do not advertise tsl/fsl or XT in terminfo.

The generic terminal status line can be implemented in any fashion, and
on hardware terminals it can be a special out-of-screen region of the
display.  Most modern terminal emulators appear to emulate the status
line in the window title; thus the notion of the tsl escape as an xterm
window title escape.

Configuration variables have been renamed:
$ts_status_format
    format string (using $status_format codes) for the terminal status line
$ts_icon_format
    format string (using $status_format codes) for the xterm icon name
$ts_enabled
    toggle for whether to issue status updates

The old configuration names exist as synonyms.

Logic flow:
* If tsl (string) is set in terminfo, mutt will use that escape to switch
  to the status area, and will use fsl to switch back to the regular
  display area.
* Otherwise, if XT (boolean) is set in terminfo, mutt will use the
  standard xterm-compatible escapes.
* Otherwise, if $TERM matches a known terminal type, mutt will use the
  standard xterm-compatible escapes.
* Otherwise, this feature is disabled.

= NOTE =

The XTerm icon escape sequence is not formalized in terminfo, so the
egregious kludge of hardcoding the escape is necessary in this case.
However, some terminal emulators (e.g. MacOS X Terminal.app) will set
the status line (window title) when the icon sequence is received.
Since there is no way to detect this behavior, the only solution is to
write your configuration to take it into account.  Rather than add a
variable to control icon escapes separately, we just provide the advice:
if you use such a terminal, you may wish to set ts_icon_format to an
empty string.  This will cause it not to be used.
version.sh: step back from $() to ``.  closes #3661
UPDATING blurb for terminal status features
Fix postpone/resume to not remove a Mail-Followup-To header  (closes #3070)

This solution changes mutt_prepare_template() to check whether the
message_id field is NULL to decide whether to wipe the message-id and
mail-followup-to headers when instantiating the message.

If we are resending a message, we don't want the previous message-id
and mail-followup-to headers.  If we are resuming a postponed message,
however, we want to keep the mail-followup-to header if any was set
before the postpone.
Close HEAD