Add Seen before: field which auto-increments when the post has been viewed

[bobbingwide]

In the Genesis-SB theme the "Seen before" field displays the value of the post meta field called _seen_before.
This field is auto-incremented each time the post is viewed individually.

I need to replicate this logic in SB.
I imagine this will have to be implemented as a new block.
It'll give me the opportunity to learn how to access post meta data.

Note: In my first attempt to simply display the current value of the field nothing is being shown for the [bw_field _seen_before] shortcode.

[bobbingwide]

Two things.

1. I managed to get the shortcode to work. The field was defined as '#theme' => false.
2. The code in Genesis-SB has been wrong for a while. It generates invalid HTML. The span's are wrong.

<div class="seen-before">Seen before: </span><span class="seen-before-value">1,468 times</div>

I'm working on the new code. So it'll be fixed there.

[bobbingwide]

Closing this as the block is now part of bigram upon which the theme is dependent. See issue #23 above.