[Footnote extension] Add a way to customize the backlink title (Pytho…

…n-Markdown#616)

Fixes Python-Markdown#610.

docs/extensions/footnotes.md

@@ -85,3 +85,9 @@ The following options are provided to configure the output:
 * **`BACKLINK_TEXT`**:
     The text string that links from the footnote definition back to the position
     in the document. Defaults to `↩`.
+
+* **`BACKLINK_TITLE`**:
+    The text string for the `title` HTML attribute of the footnote definition link.
+    `%d` will be replaced by the footnote number. Defaults to `Jump back to
+    footnote %d in the text`
+

markdown/extensions/footnotes.py

@@ -49,7 +49,12 @@ def __init__(self, *args, **kwargs):
             "BACKLINK_TEXT":
                 ["↩",
                  "The text string that links from the footnote "
-                 "to the reader's place."]
+                 "to the reader's place."],
+            "BACKLINK_TITLE":
+                ["Jump back to footnote %d in the text",
+                 "The text string used for the title HTML attribute "
+                 "of the backlink. %d will be replaced by the "
+                 "footnote number."]
         }
         super(FootnoteExtension, self).__init__(*args, **kwargs)
 
@@ -192,7 +197,7 @@ def makeFootnotesDiv(self, root):
             backlink.set("class", "footnote-backref")
             backlink.set(
                 "title",
-                "Jump back to footnote %d in the text" %
+                self.getConfig("BACKLINK_TITLE") %
                 (self.footnotes.index(id)+1)
             )
             backlink.text = FN_BACKLINK_TEXT