Split the points hooks classes into their own files
Split the post points hook into post publish and post delete hooks

Updates the related unit tests as well.

See #46
Make WordPoints_Points_Hooks::points_type() public

Next commit will explain why its needed.

See #46
Split existing instances of the post points hook on update to 1.4.0

See #46
Defer the update to 1.4.0 until the points hooks are registered

Otherwise we won’t be able to get the hook object handlers, which will
result in a fatal error.

See #46