Beginning to refactor document relationship links to reduce common code.

Beginning to refactor document relationship links to reduce common code.

My attempts here are to mimic the `pagination()` method shared by
actions. I'm tentatively adding the `$count` property to actions so that
we can query the number of notices ''being displayed'' per page prior to
calling the actual `pagination()` method itself, since document
relationship `<link>` elements need to be output inside of `showHead()`,
before `showContent()`, which is where `pagination()` is, gets called.