Don't call sit-for in right-char and left-char for visual cursor motion.

Don't call sit-for in right-char and left-char for visual cursor motion.

 src/xdisp.c (Fmove_point_visually): Invalidate the cursor position
 when moving point by using the current glyph matrix.  This avoids
 the need to force redisplay when this function is called in a
 loop.

 lisp/bindings.el (right-char, left-char): Don't call sit-for, this is
 no longer needed.  Use arithmetic comparison only for numerical
 arguments.