Add some icons and rename to internal tasklist name.

docs/manual/actions.page

docs/manual/add-new-items.page

docs/manual/applicationsmenu.page

docs/manual/clock.page

docs/manual/directorymenu.page

docs/manual/figures/Makefile.am

docs/manual/figures/actions.png

docs/manual/figures/add-new-items.png

docs/manual/figures/applicationsmenu.png

docs/manual/figures/clock.png

docs/manual/figures/directorymenu.png

docs/manual/figures/launcher.png

docs/manual/figures/pager.png

docs/manual/figures/preferences.png

docs/manual/figures/separator.png

docs/manual/figures/systray.png

docs/manual/figures/tasklist.png

docs/manual/figures/windowmenu.png

docs/manual/launcher.page

docs/manual/pager.page