Pres This:

- Change the newly added `press_this_save_post_content` filter to `press_this_save_post` and pass the $post_data array to it.
- Remove the newly added `press_this_useful_html_elements`. It only runs in compatibility mode when a URL is typed by the user.
- Remove the `press_this_suggested_content` filter. It is redundant as the suggested HTML for the editor is already filtered by `press_this_suggested_html`.
- Add some more inline docs and rename couple of vars to make the code more readable.

Fixes #34455.
Built from https://develop.svn.wordpress.org/trunk@36848


git-svn-id: https://core.svn.wordpress.org/trunk@36815 1a063a9b-81f0-0310-95a4-ce76da25c4cd