Create RFC unix cp command support

[webdesus]

Submit for discussion

[pczarn]

I disagree with this idea. It goes against the rule "There should be one-- and preferably only one --obvious way to do it." Are you sure users would want this? It would be best to get input from users.

Do we actually do exactly the same thing as cp does for all possible uses? If not, such an API be misleading.

[webdesus]

My offer was only for one method from others. My pooint is:

• Make macros function or function wich get input like cp command
• We can using another approach for copy and move, more comfortable API for rust using.
• We make just one function wrapper for our API wich compatable with cp command.
• Our API functions in fs_extra can be more than in cp.
• But for people who knows cp this approach maybe was convenient.

I'm not sure, just suggestion... So many people write in issues and comparable fs_extara with cpcommand