Initial Implementation of Auth Caching #113

TODO: certify that all auths specified when generating a sync or asyc
call from code are properly cached.

contracts/eoslib/auth.h

@@ -0,0 +1,29 @@
+/**
+ * @file auth.h
+ * @brief Defines C API for interfacing with authority caching
+ */
+#pragma once
+#include <eoslib/types.hpp>
+
+extern "C" {
+
+/**
+ * @defgroup authcache Authority Cache
+ * @brief APIs for saving, using, and clearing authorization
+ * @ingroup contractdev
+ *
+ * There are cases where one contract needs to generate a message in the name of another
+ * contract. A contract can cache the authority on the current message and then use that
+ * authority while generating a synchronous message in the future.
+ *
+ * These methods require the specified scope. An authority cached in one scope cannot be
+ * loaded in another. 
+ * 
+ * @{
+ */
+void cache_auth( AccountName scope, AccountName account, PermissionName perm );
+void load_auth( AccountName scope, AccountName account, PermissionName perm );
+void clear_auth( AccountName scope, AccountName account, PermissionName perm );
+///@} 
+
+}