bpo-10379: add 'monetary' to format_string, deprecate format

Add the 'monetary' parameter to format_string so that all
uses of format can be converted to format_string.  Adjust
the documentation accordingly, and add a deprecation
warning when format is used.
diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index 4a9fcba..67d3281 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -381,8 +381,8 @@
 
         for i in range(-10, 10):
             x = 1234567890.0 * (10.0 ** i)
-            self.assertEqual(locale.format('%g', x, grouping=True), format(x, 'n'))
-            self.assertEqual(locale.format('%.10g', x, grouping=True), format(x, '.10n'))
+            self.assertEqual(locale.format_string('%g', x, grouping=True), format(x, 'n'))
+            self.assertEqual(locale.format_string('%.10g', x, grouping=True), format(x, '.10n'))
 
     @run_with_locale('LC_NUMERIC', 'en_US.UTF8')
     def test_int__format__locale(self):
@@ -390,7 +390,7 @@
 
         x = 123456789012345678901234567890
         for i in range(0, 30):
-            self.assertEqual(locale.format('%d', x, grouping=True), format(x, 'n'))
+            self.assertEqual(locale.format_string('%d', x, grouping=True), format(x, 'n'))
 
             # move to the next integer to test
             x = x // 10