Change the image header magic

Since we've changed the meaning of several fields in the header, bump
the header to a new magic number.  The fields that are still present are
in the same place, but all of the signature and TLV information is moved
into the TLV itself, which is still immediately after the image.

As of this commit, this defines the new image header/TLV format used for
1.0.

Based on work by Marko Kiiskila <marko@runtime.io>

Signed-off-by: Marko Kiiskila <marko@runtime.io>
Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/sim/src/main.rs b/sim/src/main.rs
index 9e38172..713bb52 100644
--- a/sim/src/main.rs
+++ b/sim/src/main.rs
@@ -750,7 +750,7 @@
 
     // Generate a boot header.  Note that the size doesn't include the header.
     let header = ImageHeader {
-        magic: 0x96f3b83c,
+        magic: 0x96f3b83d,
         tlv_size: tlv.get_size(),
         _pad1: 0,
         hdr_size: 32,