Option to flatten class tree

[jaapio]

Not in all situations, it is required to have the full class tree.

php_code_sniffer, for example, wants to generate documentation based on the class docblocks and properties. But rest of the api docs are not relevant to all users.
But also the hierarchy is not relevant add this level.

Could we come up with a solution to make this possible in a template or are custom templates required for this situation? Could we provide a way to filter elements based on their type?