Fix bugzilla bug 225301.  r=jpierre. This patch does the following: 1. Fixes the Usage message to document the command line options. 2. Changes the "decode" function to    a) report an error on bad signatures, only when decoding the input file,       not when decoding an ancillary "enveloped file".    b) only output the contents of the "detached content" file (-c option)       when that file's content was actually used in the computation. 3. Sundry other cleanup and added comments.
Fix bugzilla bug 225301.  r=jpierre. This patch does the following:
1. Fixes the Usage message to document the command line options.
2. Changes the "decode" function to
   a) report an error on bad signatures, only when decoding the input file,
      not when decoding an ancillary "enveloped file".
   b) only output the contents of the "detached content" file (-c option)
      when that file's content was actually used in the computation.
3. Sundry other cleanup and added comments.

ekr/nss-old,ekr/nss-old,nmav/nss,ekr/nss-old,ekr/nss-old,nmav/nss,nmav/nss,nmav/nss,ekr/nss-old,ekr/nss-old,nmav/nss,nmav/nss,nmav/nss,ekr/nss-old