Lightbox: Changed lb- and -lb to lbx- and -lbx

Related to #3911.

Introduces the following changes:

1. lb-hide-gal to lbx-hide-gal
2. lb-title to lbx-title
3. lb-iframe to lbx-iframe
4. lb-gal to lbx-gal
5. lb-modal to lbx-modal
6. wb-lb to wb-lbx