Checkout process, a kind of.

I've added a new class (core/class.order.php) that manages everything
regarding the vdorders and vdbilling tables (contains orders and
contains billing info).
I've also edited a few comments and controllers (controlers/*).
Also created new objects in main.js: form and helper which, one should
manage all the form validations and such and the other will manage
general functions such as togglers.
A few other small edits here and there.