Add bash-completion script for notmuch.

It's not much of a script, (we don't have that many commands after
all), but it's the kind of thing that's nice to have and gives the
tool a slightly more polished feel.

notmuch-completion.bash

@@ -0,0 +1,50 @@
+# Bash completion for notmutch
+#
+# Copyright © 2009 Carl Worth
+#
+# This program 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.
+#
+# This program 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 this program.  If not, see http://www.gnu.org/licenses/ .
+#
+# Author: Carl Worth <cworth@cworth.org>
+#
+# Based on "notmuch help" as follows:
+#
+# Usage: notmuch <command> [args...]
+#
+# Where <command> and [args...] are as follows:
+#
+#	setup
+#
+#	new
+#
+#	search <search-term> [...]
+#
+#	show <thread-id>
+#
+#	dump [<filename>]
+#
+#	restore <filename>
+
+_notmuch()
+{
+    current="$2"
+
+    commands="help setup new search show dump restore"
+
+    COMPREPLY=()
+
+    if [ "$COMP_CWORD" = "1" ]; then
+	COMPREPLY=( $(compgen -W "${commands}" -- ${current}) )
+    fi
+}
+complete -o default -o bashdefault -F _notmuch notmuch