Make 'cdr' command interactive when multiple matches are found

When multiple matches are reported, prompt the user for a match index
and then re-issue 'cdr <id>'
Colorize match output in cdr command

Add an explicit -color option to rd to enable colorized output
when stdout is not a terminal and use this in the 'cdr'
bash command.
Sort matches in output

This ensures that we get a consistent ordering if the same set of
matches appear in multiple queries.

The initial sort order is a simple lexicographical sort
of the dir paths