Merge edit_form_advanced and edit_page_form hooks

[solarissmoke]

In the era of custom post types, having to register one hook for pages (edit_page_form) and one for all other post types (edit_form_advanced) to add stuff to the post editor seems a bit weird. I think that these should be consolidated.

I guess the most backward-compatible way would be to deprecate both of these hooks and add one that fires for all post types, and passes the post type as an argument?

[solarissmoke]

Something like this

[solarissmoke]

The introduction of the edit_form_after_editor (r22446) resolves the issue that I had, so unless anyone still feels that having a separate hook for pages is unnecessary, this can probably be closed.

[nacin]

There are a *lot* of places that fire different hooks for pages versus everything else. Not worth fixing this one without a systematic approach.