fix manual for operator>>

manual filtered bbox kernel, ref counting

manual orientation: NO (only when points have same delta, so don't document)

clean manual AK (concepts like Polynomial_1_2, access to a() b() c() ?
used in solve to check that solutions are the same)

rendre Bbox filtered kernel completement generique -> 
	utilisation dans linear kernel aussi

echecs de filtres 

voir make_x_monotone pour que ca retourne des arcs 
(necessite bricolage de la traits car Arr_2 demande des Object)

interface intersect avec plusieurs outputIt types (types de retour differents)

--> a transferer dans linear kernel ? 
	- unoriented equal (pb general orientation dans noyau cgal...)

construct intersection for *arcs* should use solve or solve in range

----------- done (?)
memory leaks in Filtered_bbox_circular_kernel_2
from Andreas: 
- there are new statements in constructors having no corresponding 
delete statements.
This concerns the files in the directory:
CGAL-3.3.1/include/CGAL/Filtered_bbox_circular_kernel_2/...with_bbox_2.h
It should be enough to add destructors and add conditional
deletes.
Reading the code I think that the IO routines also don't
do what they should do, namely computing new bboxes.