Url field formats need an alt template

[spalger]

Currently, when a field is url formatted, the rendered text for that value is always the url that it points to but this regularly causes unwieldy values.

There should be a second template as a part of the url field format that allows you to specify what the text representation of that url should be as opposed to the href/src template (need to work on naming).

• The url template
  • defaults to the field value itself
  • used as the href for <a> tags
  • used as the src for <img> tags
  • has value and rawValue variables available to it.
• The label template
  • defaults to the url
  • used as the content of <a> tags
  • used as the alt for <img> tags
  • has value, rawValue, and url variables available to it.

[spalger]

Closed by #3748