It is not switched on by default and must be enabled with the -G
flag. When using ls -G the output behaviour is modified with ANSI
colour sequences wrapped around filenames to help distinguish file
types. (Colours can be redefined in the LSCOLORS environment
variable as described in the manual page.)
Colour support is silently disabled (if switched on) if stdout
isn't a tty.
Based on: asami's colorls port.
PR: bin/18900 && ports/18616.
9ad4da2e70