Select SeeAlso template based on element

[nichtich]

<!-- comma-separated -->
<span seealso-api="http://example.org/" seealso-id="123"/>
<!-- list -->
<ul seealso-api="http://example.org/" seealso-id="123"/>
 <ol seealso-api="http://example.org/" seealso-id="123"/>
<!-- image -->
<img seealso-api="http://example.org/" seealso-id="123"/>
<!-- custom template -->
<div seealso-api="http://example.org/" seealso-id="123">
 ...
</div>
<!-- custom template, referenced -->
<div seealso-api="http://example.org/" seealso-id="123" template-url="..." />