Speed up vertical-motion when screen coordinates are known

Speed up vertical-motion when screen coordinates are known

 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.