Improve and make resize internals simpler

src/client.c

themes/default/bottom-active.xpm

themes/default/bottom-inactive.xpm

themes/default/bottom-left-active.xpm

themes/default/bottom-left-inactive.xpm

themes/default/bottom-right-active.xpm

themes/default/bottom-right-inactive.xpm

themes/default/close-active.xpm

themes/default/close-inactive.xpm

themes/default/hide-active.xpm

themes/default/hide-inactive.xpm

themes/default/left-active.xpm

themes/default/left-inactive.xpm

themes/default/maximize-active.xpm

themes/default/maximize-inactive.xpm

themes/default/maximize-toggled-active.xpm

themes/default/maximize-toggled-inactive.xpm

themes/default/menu-active.xpm

themes/default/menu-inactive.xpm

themes/default/right-active.xpm