Controlling S/MIME spec is now v3.2 (RFC 5751)

Changes almost exclusively deal with pkcs7 data.

One new feature to be aware of: a full MIME message can now be wrapped
within a rfc822 part in order to provide verification protection to non-MIME
Headers (e.g. To, From, Cc, Subject).  According to spec, it is up to
MUA to determine how to merge these "inner" headers with the "outer"
headers for purposes of display.  Think we are fine for now - our rfc822
MIME Viewer already displays these basic headers at the top of a rfc822
block, which would be contained within the S/MIME verification box.  We
only guarantee validity of data within that box so that is consistent
with this display.

imp/docs/RFCS

@@ -125,12 +125,12 @@ MIME
            Languages, and Continuations
 :RFC 2387: The MIME Multipart/Related Content-type
 :RFC 2392: Content-ID and Message-ID Uniform Resource Locators
-:RFC 2633: S/MIME Version 3 Message Specification
 :RFC 3156: MIME Security with OpenPGP
 :RFC 3282: Content Language Headers
 :RFC 3464: An Extensible Message Format for Delivery Status Notifications
 :RFC 3803: Content Duration MIME Header Definition
 :RFC 3834: Recommendations for Automatic Responses to Electronic Mail
+:RFC 5751: S/MIME Version 3.2 Message Specification
 
 
 Non-RFC Features

imp/lib/Mime/Viewer/Smime.php

@@ -12,7 +12,7 @@
  */
 
 /**
- * Renderer for viewing/decrypting of S/MIME messages (RFC 2633).
+ * Renderer for viewing/decrypting of S/MIME v3.2 messages (RFC 5751).
  *
  * This class handles the following MIME types:
  *   application/pkcs7-mime