add nullsfirst() / nullslast() to top-level imports

Change-Id: Ieefcc4c30c1c17f43f2908d961e00815bae862bb
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/378

doc/build/changelog/unreleased_11/nulls_import.rst

@@ -0,0 +1,7 @@
+.. change::
+    :tags: bug, sql
+    :versions: 1.2.0b4
+
+    Added :func:`.nullsfirst` and :func:`.nullslast` as top level imports
+    in the ``sqlalchemy.`` and ``sqlalchemy.sql.`` namespace.  Pull request
+    courtesy Lele Gaifax.

lib/sqlalchemy/__init__.py

@@ -38,6 +38,8 @@ from .sql import (
     modifier,
     not_,
     null,
+    nullsfirst,
+    nullslast,
     or_,
     outerjoin,
     outparam,

lib/sqlalchemy/sql/__init__.py

@@ -53,6 +53,8 @@ from .expression import (
     modifier,
     not_,
     null,
+    nullsfirst,
+    nullslast,
     or_,
     outerjoin,
     outparam,