Replace list mode in command line with option -lt

- When the target is -lt or --listTargets the command line will show the
  list of targets with dependencies
Add option in the command line option to list targets
Document the option -lt to list targets.

- The option -lt or --listTargets show the list of targets.
Merge pull request #571 from ovu/feature/ListTargetsInCommandLine

Feature/list targets in command line