bug: local echo when stdin is a file

Disable local if stdout is a terminal, instead of stdin. Because stdin
may be a file, but output may still end up on a terminal with local echo.
ui: remove legend and title

The Legend and title use some space and doesn't provide any useful
information in most cases. Move legend to man-page and use -V for
version information.
ui: selective updating of targets

Have the update call supply the updated target for selective redrawing.
main: remove statistics

Remove unused counters and statistics display.