Add _init() and _free() for hash modules
diff --git a/include/polarssl/sha1.h b/include/polarssl/sha1.h
index 57a731b..cb0c436 100644
--- a/include/polarssl/sha1.h
+++ b/include/polarssl/sha1.h
@@ -67,6 +67,20 @@
 sha1_context;
 
 /**
+ * \brief          Initialize SHA-1 context
+ *
+ * \param ctx      SHA-1 context to be initialized
+ */
+void sha1_init( sha1_context *ctx );
+
+/**
+ * \brief          Clear SHA-1 context
+ *
+ * \param ctx      SHA-1 context to be cleared
+ */
+void sha1_free( sha1_context *ctx );
+
+/**
  * \brief          SHA-1 context setup
  *
  * \param ctx      context to be initialized