ignore none numeric inputs

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
add check for various error cases

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
fix off by one error

Caused by fscanf() reading EOF as a number.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
always use +-1 for q1 and q3 position

This is more often correct than incorrect.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
add --whiskers check

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
add new line when results output is empty

Signed-off-by: Sami Kerola <kerolasa@iki.fi>