cli_wallet: Expose get_private_key()

libraries/wallet/include/graphene/wallet/wallet.hpp

@@ -356,6 +356,12 @@ class wallet_api
        */
       string                            get_wallet_filename() const;
 
+      /**
+       * Get the WIF private key corresponding to a public key.  The
+       * private key must already be in the wallet.
+       */
+      string                            get_private_key( public_key_type pubkey )const;
+
       /**
        * @ingroup Transaction Builder API
        */
@@ -1301,6 +1307,7 @@ FC_API( graphene::wallet::wallet_api,
         (get_global_properties)
         (get_dynamic_global_properties)
         (get_object)
+        (get_private_key)
         (load_wallet_file)
         (normalize_brain_key)
         (get_limit_orders)

libraries/wallet/wallet.cpp

@@ -2800,6 +2800,11 @@ string wallet_api::get_key_label( public_key_type key )const
    return string();
 }
 
+string wallet_api::get_private_key( public_key_type pubkey )const
+{
+   return key_to_wif( my->get_private_key( pubkey ) );
+}
+
 public_key_type  wallet_api::get_public_key( string label )const
 {
    try { return fc::variant(label).as<public_key_type>(); } catch ( ... ){}