Rename 'draw' or 'drawcall' to action

* There's not a good accepted terminology for this kind of event, and for
  historical reasons 'drawcall' has been the accepted term, even though
  that can be quite confusing when a dispatch or a copy is a 'drawcall'.
* This is particularly highlighted by the event browser filters where
  $draw() includes draws and dispatches, but $dispatch() only includes
  dispatches, it's hard to intuitively understand why $draw() matches all
  of these calls.
* As a result we've defined the term 'action' to cover these types of
  events in the same way that we defined 'event' in the first place to
  mean a single atomic API call.

docs/python_api/ui_extension_tutorial/__init__.py

@@ -56,16 +56,16 @@ class Window(qrd.CaptureViewer):
         pass
 
     def OnEventChanged(self, event):
-        draw = self.ctx.GetDrawcall(event)
+        action = self.ctx.GetAction(event)
 
         breadcrumbs = ''
 
-        if draw is not None:
-            breadcrumbs = '@{}: {}'.format(draw.eventId, draw.name)
+        if action is not None:
+            breadcrumbs = '@{}: {}'.format(action.eventId, action.name)
 
-            while draw.parent is not None:
-                draw = draw.parent
-                breadcrumbs = '@{}: {}'.format(draw.eventId, draw.name) + '\n' + breadcrumbs
+            while action.parent is not None:
+                action = action.parent
+                breadcrumbs = '@{}: {}'.format(action.eventId, action.name) + '\n' + breadcrumbs
 
         self.mqt.SetWidgetText(self.breadcrumbs, "Breadcrumbs:\n{}".format(breadcrumbs))