Reverting smacs and rmacs to the xterm defaults.

These are needed by ncurses to correctly handle the switch between line
drawing. The changes to the alternative characterset code already fixed the
urwid hack.
Avoid failing when embedding with a Window id of 0

I'd like to let st run with its own window when trying to embed it to a window with id 0 instead of exiting with an error.
Port to wayland
Adapt to new wld_draw_text