Rename {filter_format}.name to .title and replace .format with machine-readable .name

Filters have an internal name, like "filter_html", so both $filter->name and {filter}.name make sense, because they refer to a machine name.

Formats, however, use a user-configurable title, like "Filtered HTML". But that value is currently stored in {filter_format}.name instead of .title. Totally confusing.

{filter_format}.name should be renamed to {filter_format}.title.

And while being there, we also want to fix that filter.test file, where the code refers to "filter" instead of "format" all over the place, but meaning "format" in reality.