UV_OT_lightmap_pack: Distinction between edit and object modes

I don't even know why this operator was ever made to work in object mode.
That said, since it does, we should have different options for it
(or rather, always do all faces for it).

release/scripts/startup/bl_operators/uvcalc_lightmap.py

@@ -647,11 +647,35 @@ class LightMapPack(Operator):
         default=0.1,
     )
 
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+
+        is_editmode = context.active_object.mode == 'EDIT'
+        if is_editmode:
+            layout.prop(self, "PREF_CONTEXT")
+
+        layout.prop(self, "PREF_PACK_IN_ONE")
+        layout.prop(self, "PREF_NEW_UVLAYER")
+        layout.prop(self, "PREF_APPLY_IMAGE")
+        layout.prop(self, "PREF_IMG_PX_SIZE")
+        layout.prop(self, "PREF_BOX_DIV")
+        layout.prop(self, "PREF_MARGIN_DIV")
+
+    @classmethod
+    def poll(cls, context):
+        ob = context.active_object
+        return ob and ob.type == 'MESH'
+
     def execute(self, context):
         kwargs = self.as_keywords()
         PREF_CONTEXT = kwargs.pop("PREF_CONTEXT")
 
-        if PREF_CONTEXT == 'SEL_FACES':
+        is_editmode = context.active_object.mode == 'EDIT'
+
+        if not is_editmode:
+            kwargs["PREF_SEL_ONLY"] = False
+        elif PREF_CONTEXT == 'SEL_FACES':
             kwargs["PREF_SEL_ONLY"] = True
         elif PREF_CONTEXT == 'ALL_FACES':
             kwargs["PREF_SEL_ONLY"] = False