DOCUMENT_TODO

OK	Terminal.js file and object separated from termkit.js
OK	Terminal#object2attr
OK	Move ScreenBuffer#color2index to termkit.color2index (through misc.js)
OK	Terminal#put() that mimic ScreenBuffer#put()
OK	Create a Element object, that is recursive: it can have Element children that can cycle focus using TAB and SHIFT_TAB
OK	Button should inherit from Element
OK	Document root Element
OK	Move inputField() area mode to an InputText object that inherit from Element
OK	Turn Forms into a Element of Elements
OK	Layout should be a Element, and...
OK	... and each leaf boxes' ScreenBuffer should be Elements too
OK	Full redraw of the whole document

	Use Bobbox as the box-model manager