Restore a couple of constants that got los in the refactor

Author: mwcraig

astrowidgets/interface_definition.py

@@ -1,6 +1,12 @@
 from typing import Protocol, runtime_checkable, Any
 from abc import abstractmethod
 
+# Allowed locations for cursor display
+ALLOWED_CURSOR_LOCATIONS = ['top', 'bottom', None]
+
+# List of marker names that are for internal use only
+RESERVED_MARKER_SET_NAMES = ['all']
+
 
 @runtime_checkable
 class ImageViewerInterface(Protocol):

astrowidgets/tests/test_api_ginga.py

@@ -10,8 +10,8 @@
 
 from ginga.ColorDist import ColorDistBase
 
-from astrowidgets.ginga import ImageWidget, ALLOWED_CURSOR_LOCATIONS
-from astrowidgets.interface_definition import ImageViewerInterface
+from astrowidgets.ginga import ImageWidget
+from astrowidgets.interface_definition import ImageViewerInterface, ALLOWED_CURSOR_LOCATIONS
 
 
 def test_consistent_interface():

astrowidgets/tests/test_ginga_widget.py

@@ -7,7 +7,8 @@
 from astropy.nddata import CCDData
 from astropy.coordinates import SkyCoord
 
-from ..ginga import ImageWidget, RESERVED_MARKER_SET_NAMES
+from ..ginga import ImageWidget
+from astrowidgets.interface_definition import RESERVED_MARKER_SET_NAMES
 
 
 def _make_fake_ccd(with_wcs=True):