smaller heights for aux and status panes
toggle action for commands

if the pane is closed or nothing is running in it, calls make().
if the command is alive, toggles the pane.
implement minimizing layouts

instead of toggling the main pane, the default is now to send the toggle
command to the make layout, which uses the first open pane to relay all
size-related tasks.

minimizing a pane now only applies to their stacking direction, which is
a no-op when there is only one open pane in the layout, like when the
default make pane is open, so minimizing it means actually minimizing
the make layout.

toggling and minimizing have been refactored into a base class View.
close function for layout
remove minimize spec