Default theme implementation for a single field in a view.
It is not actually used in default views, as this is registered as a theme function which has better performance. For single overrides, the template is perfectly okay.
Available variables:
When fetching output from the row this construct should be used: data = row[field.field_alias]
The above will guarantee that you'll always get the correct data, regardless of any changes in the aliasing that might happen if the view is modified.
template_preprocess_views_view_field()