Enhance golo diagnose command to support directories

this command is valid
$ golo diagnose samples/
$
Enhance golo doc command to support directories

this command is valid
$ golo doc samples/
$
Add --usage to Golo script

this option --usage print the help for a command

this command is valid
$ golo --usage run
Runs compiled Golo code
Usage: run [options] Program arguments
  Options:
        --classpath
       Classpath elements (.jar and directories)
       Default: []
  *     --module
       The Golo module with a main function
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