Code review comment for lp://qastaging/~benoit.pierre/bzrtools/colordiff_when_tty

OK, so how about a --color option that works like for ls:

# ls --color=never
-> no colors
# ls --color=never > listing
-> no colors
# ls --color=auto
-> colors
# ls --color=auto > listing
-> no colors
# ls --color=always
-> colors
# ls --color=always > listing
-> colors

'auto' being the default mode.