NEW : arbitrary slice action to customize it (angle, slice number).
	NEW : widget to set up slice number and angles.

NEW : arbitrary slice number is initialized to the max of the 3 others axes slices number (axial, coronal, sagital).
FIXED : action families which contain only one action are displayed like others : a submenu of the family name, and an entry of the name of the action (previously the family sub-menu was not displayed, shorten the menu to the action directly). I think the family menu shows important nformation. To be debated.

git-svn-id: svn+ssh://scm.forge.imag.fr/var/lib/gforge/chroot/scmrepos/svn/camitk/trunk/camitk@228 ec899d31-69d1-42ba-9299-647d76f65fb3