Make EVP_Digest*() routines return a value.

TODO: update docs, and make soe other routines
which use EVP_Digest*() check return codes.
diff --git a/CHANGES b/CHANGES
index 36acb79..d52d19f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3,6 +3,11 @@
 
  Changes between 0.9.6 and 0.9.7  [xx XXX 2000]
 
+  *) Modify EVP_Digest*() routines so they now return values. Although the
+     internal software routines can never fail additional hardware versions
+     might.
+     [Steve Henson]
+
   *) Clean up crypto/err/err.h and change some error codes to avoid conflicts:
 
      Previously ERR_R_FATAL was too small and coincided with ERR_LIB_PKCS7