src/indent.c (Fvertical_motion): Accept an additional argument
CUR-COL and use it as the starting screen coordinate.
src/window.c (window_scroll_line_based, Fmove_to_window_line): All
callers of vertical-motion changed.
doc/lispref/positions.texi (Screen Lines): Update the documentation of
vertical-motion to document the new additional argument.
403cb178c7