Support coloured output for ls and grep commands

[ianthomas23]

Support coloured output for ls and grep commands. This is actually a surprisingly small change in the code just to set the TERM environment variable, now that aliases are set up to use colour in both ls and grep commands by default. It uses the default ls colours which can be checked using dircolors --print-ls-colors; these could be overridden by setting an LS_COLORS env var.