BSX-21 Import Bitcoin Private Key from String

include/fc/crypto/sha256.hpp

@@ -11,6 +11,7 @@ class sha256
   public:
     sha256();
     explicit sha256( const string& hex_str );
+    explicit sha256( const char *data );
 
     string str()const;
     operator string()const;

src/crypto/sha256.cpp

@@ -8,6 +8,7 @@
 namespace fc {
 
     sha256::sha256() { memset( _hash, 0, sizeof(_hash) ); }
+    sha256::sha256( const char *data ) { memcpy(_hash, data, sizeof(_hash) ); }
     sha256::sha256( const string& hex_str ) {
       fc::from_hex( hex_str, (char*)_hash, sizeof(_hash) );  
     }