(Fx_create_frame): Default Qvertical_scroll_bars to `left'.

(Fx_create_frame): Default Qvertical_scroll_bars to `left'.

Add the symbol `right'; this symbol is used to indicate
that a right-side scroll bar is wanted.
(x_set_vertical_scroll_bars): Check for left<->right<->none
scroll bar changes, and modify the vertical scroll bar type as appropriate.
(x_figure_window_size): Use new SET_FRAME_WIDTH macro.
(Fx_create_frame): Likewise.
(Fx_horizontal_line): Use new macro WINDOW_LEFT_MARGIN.