CLI/show: support --duplicate for structured output

This introduces a new mandatory key for message structures, namely
"duplicate". Per convention in devel/schemata this does _not_ increase
the format version. This means that clients are responsible for
checking that it exists, and not crashing if it does not.

The main functional change is teaching mime_node_open to understand a
'duplicate' argument.

Support for --duplicate in notmuch-reply would make sense, but we
defer it to a later commit.

1 files changed, 1 insertions, 0 deletions

diff --git a/devel/schemata b/devel/schemata
index 01810888..66bcdbed 100644
--- a/devel/schemata
+++ b/devel/schemata
@@ -83,6 +83,7 @@ message = {
 
     headers:        headers,
     crypto:         crypto,
+    duplicate:      integer,
     body?:          [part]    # omitted if --body=false
 }