More robust In-Reply-To parsing

Use `parse_message_id` on the header contents before using it.

Database still stores the raw value.

src/mimeparser.rs

@@ -2955,4 +2955,46 @@ On 2020-10-25, Bob wrote:
             Some("Mr.6Dx7ITn4w38.n9j7epIcuQI@outlook.com".to_string())
         );
     }
+
+    #[async_std::test]
+    async fn test_long_in_reply_to() -> Result<()> {
+        let t = TestContext::new_alice().await;
+
+        // A message with a long Message-ID.
+        // Long message-IDs are generated by Mailjet.
+        let raw = br###"Date: Thu, 28 Jan 2021 00:26:57 +0000
+Chat-Version: 1.0\n\
+Message-ID: <ABCDEFGH.1234567_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA@mailjet.com>
+To: Bob <bob@example.org>
+From: Alice <alice@example.org>
+Subject: ...
+
+Some quote.
+"###;
+        dc_receive_imf(&t, raw, "INBOX", 1, false).await?;
+
+        // Delta Chat generates In-Reply-To with a starting tab when Message-ID is too long.
+        let raw = br###"In-Reply-To:
+	<ABCDEFGH.1234567_AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA@mailjet.com>
+Date: Thu, 28 Jan 2021 00:26:57 +0000
+Chat-Version: 1.0\n\
+Message-ID: <foobar@example.org>
+To: Alice <alice@example.org>
+From: Bob <bob@example.org>
+Subject: ...
+
+> Some quote.
+
+Some reply
+"###;
+
+        dc_receive_imf(&t, raw, "INBOX", 2, false).await?;
+
+        let msg = t.get_last_msg().await;
+        assert_eq!(msg.get_text().unwrap(), "Some reply");
+        let quoted_message = msg.quoted_message(&t).await?.unwrap();
+        assert_eq!(quoted_message.get_text().unwrap(), "Some quote.");
+
+        Ok(())
+    }
 }