Add way to override grid action label rendering

so that custom HTML can be embedded in there somehow..

tailbone/grids/core.py

@@ -1434,6 +1434,17 @@ class GridAction(object):
             return self.url(row, i)
         return self.url
 
+    def render_label(self):
+        """
+        Render the label "text" within the actions column of a grid
+        row.  Most actions have a static label that never varies, but
+        you can override this to add e.g. HTML content.  Note that the
+        return value will be treated / rendered as HTML whether or not
+        it contains any, so perhaps be careful that it is trusted
+        content.
+        """
+        return self.label
+
 
 class URLMaker(object):
     """