Define sha256::hash( sha256 )

include/fc/crypto/sha256.hpp

@@ -21,6 +21,7 @@ class sha256
 
     static sha256 hash( const char* d, uint32_t dlen );
     static sha256 hash( const string& );
+    static sha256 hash( const sha256& );
 
     template<typename T>
     static sha256 hash( const T& t ) 

src/crypto/sha256.cpp

@@ -40,10 +40,16 @@ namespace fc {
       e.write(d,dlen);
       return e.result();
     }
+
     sha256 sha256::hash( const string& s ) {
       return hash( s.c_str(), s.size() );
     }
 
+    sha256 sha256::hash( const sha256& s )
+    {
+        return hash( s.data(), sizeof( s._hash ) );
+    }
+
     void sha256::encoder::write( const char* d, uint32_t dlen ) {
       SHA256_Update( &my->ctx, d, dlen); 
     }