emacs: add notmuch-version.el.tmpl and create notmuch-version.el from it

The notmuch cli program and emacs lisp versions may differ (especially
in remote usage). It helps to resolve problems if we can determine
the versions of notmuch cli and notmuch emacs mua separately.

The build process now creates notmuch-version.el from template file
by filling the version info to notmuch-emacs-version variable.

emacs/.gitignore

@@ -1,2 +1,3 @@
 .eldeps*
 *.elc
+notmuch-version.el

emacs/Makefile.local

@@ -17,7 +17,14 @@ emacs_sources := \
 	$(dir)/notmuch-crypto.el \
 	$(dir)/notmuch-tag.el \
 	$(dir)/coolj.el \
-	$(dir)/notmuch-print.el
+	$(dir)/notmuch-print.el \
+	$(dir)/notmuch-version.el
+
+$(dir)/notmuch-version.el: $(dir)/Makefile.local version.stamp
+$(dir)/notmuch-version.el: $(dir)/notmuch-version.el.tmpl
+	@sed -e 's/%AG%/Generated file (from $(<F)) -- do not edit!/' \
+	     -e 's/%VERSION%/"$(VERSION)"/' $< > $@
+
 
 emacs_images := \
 	$(srcdir)/$(dir)/notmuch-logo.png
@@ -71,4 +78,4 @@ endif
 	mkdir -p "$(DESTDIR)$(emacsetcdir)"
 	install -m0644 $(emacs_images) "$(DESTDIR)$(emacsetcdir)"
 
-CLEAN := $(CLEAN) $(emacs_bytecode)
+CLEAN := $(CLEAN) $(emacs_bytecode) $(dir)/notmuch-version.el

emacs/notmuch-version.el.tmpl

@@ -0,0 +1,23 @@
+;; -*- emacs-lisp -*-
+;;
+;; %AG%
+;;
+;; This file is part of Notmuch.
+;;
+;; Notmuch is free software: you can redistribute it and/or modify it
+;; under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+;;
+;; Notmuch is distributed in the hope that it will be useful, but
+;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;; General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with Notmuch.  If not, see <http://www.gnu.org/licenses/>.
+
+(defconst notmuch-emacs-version %VERSION%
+  "Version of Notmuch Emacs MUA.")
+
+(provide 'notmuch-version)

emacs/notmuch.el

@@ -61,6 +61,10 @@
 (require 'notmuch-message)
 (require 'notmuch-parser)
 
+(unless (require 'notmuch-version nil t)
+  (defconst notmuch-emacs-version "unknown"
+    "Placeholder variable when notmuch-version.el[c] is not available."))
+
 (defcustom notmuch-search-result-format
   `(("date" . "%12s ")
     ("count" . "%-7s ")