layers: split draw_wpt into make_wpts_tmpl and plot_wpts_tmpl (will be used for caching)
cairo_wrapper: add range()
layers/draw_wpt: add GObj with caching (not used)
gred: gobj_comp.h - simple compound for gobjects
(Layer revolution starts -- something can be broken) -- use separate workplanes for wpts, trks, maps, srtm