enable `-Dscala.color` in shell scripts

[adriaanm]

We should enable color output in the shell scripts so that programmatic launching still gets the plain old version, but users by default get the nicer experience.

[dwijnand]

To enable it globally for sbt console you can create a ~/.sbt/0.13/colour.sbt with:

initialize ~= (_ => if (ConsoleLogger.formatEnabled) sys.props("scala.color") = "true")

[retronym]

Note that some environments still call the scripts that don't really want colorization, e.g. emacs, sublime.

[retronym]

http://stackoverflow.com/questions/911168/how-to-detect-if-my-shell-script-is-running-through-a-pipe

[gourlaysama]

PR: scala/scala#5663 :)