refactor next_previous block view markup
refactor next_previous block view markup

just cleaned up the markup -- no functional changes, and no changes to outputted html.
TimDix/concrete5,avdevs/concrete5,avdevs/concrete5,MichaelMaar/concrete5,matt9mg/concrete5,avdevs/concrete5,MichaelMaar/concrete5,TimDix/concrete5,MichaelMaar/concrete5,matt9mg/concrete5,TimDix/concrete5,matt9mg/concrete5