Redo labelformat to make it more xhtmlable.
Redo labelformat to make it more xhtmlable.

* if the first character in a label is not alpha, prefix the label with
  a "L".
* map every character that's not alphanumeric, "_", "-", ":", or "." into
  a ".".

binki/discount,davidfstr/discount,binki/discount,binki/discount,binki/discount,OliverLetterer/discount,OliverLetterer/discount,gm2bv/discount,davidfstr/discount,gm2bv/discount,davidfstr/discount,gm2bv/discount,davidfstr/discount,gm2bv/discount,OliverLetterer/discount,binki/discount