Test program for IsTerminal() in package github.com/pebbe/util

This is how it should work (on linux):

~ go get github.com/pebbe/util 
~ go get github.com/pebbe/util/isatty 
~ isatty 
stdin:  true 
stdout: true 
stderr: true 
~ isatty | cat 
stdin:  true 
stdout: false 
stderr: true 
~ isatty 2> /dev/null 
stdin:  true 
stdout: true 
stderr: false 
~ isatty < ~/.bashrc 
stdin:  false 
stdout: true 
stderr: true 
~ echo | isatty 
stdin:  false 
stdout: true 
stderr: true