closefigures and docking tools

Clear figures window so next figure will draw in 1st (upper left tile), + docking control

Users often wish to draw figures IN A SPECIFIC ORDER into the figures window tiles... but have no programmatic control over where it starts. The first figure goes into the last tile whether programmatically selected, or clicked on even if empty! clearfigures.m clears the figures window and leaves the focus in the upper left tile. fig_dock and fig_undock control docking for individual figures and defaults. (also tested on 2013b)