Metabox actionhook and some formatting
Class contained in condination statement

This way an extension could override this class.
Update options and post_meta values, settings

Downwards compatible, changed post_meta and option values into true
boolean rather than text. The problem was that empty( $option ) or
!$option would falsly return true if the settings was set (to false).

Added few filters to get default settings and tooltips. Added actions
for admin page. This way new settings can easily be added. New defaults
and tooltips even so.