Make error output useful in emacs compiler mode

Format misspelled words so emacs can use the lines to jump directly to
the bad content. Other editors with similar modes for reading compiler
output should be able to use this, too.

sphinxcontrib/spelling/builder.py

@@ -118,12 +118,12 @@ def write_doc(self, docname, doctree):
 
                 # Check the text of the node.
                 for word, suggestions in self.checker.check(node.astext()):
-                    msg_parts = [docname]
+                    msg_parts = [docname + '.rst']
                     if lineno:
-                        msg_parts.append(darkgreen('(line %3d)' % lineno))
+                        msg_parts.append(darkgreen(str(lineno)))
                     msg_parts.append(red(word))
                     msg_parts.append(self.format_suggestions(suggestions))
-                    msg = ' '.join(msg_parts)
+                    msg = ':'.join(msg_parts)
                     self.info(msg)
                     self.output.write(u"%s:%s: (%s) %s\n" % (
                         self.env.doc2path(docname, None),