To prevent nested slashes in DB when item meta key contains quotes.
This is in line with WordPress' behaviour - see update_meta() in wp-includes/meta.php
- Removed post type classes. Since they were always loaded, there was
no benefit having them split up. Combined meaning less hooked in
methods.
- Stopped loading some function files and sessions in the admin area.
They are not needed there.
- Made a few admin page classes static as they are stateless