[R-Forge #2675] Document that copy(names(DT)) may be needed

[arunsrinivasan]

Submitted by: Matt Dowle; Assigned to: Matt Dowle; R-Forge link

As raised here :

http://stackoverflow.com/questions/15913417/why-does-data-table-update-non-data-table-object-by-reference

and here :

http://stackoverflow.com/questions/18662715/colnames-being-dropped-in-data-table-in-r

Probably should go in ?copy.

Or, maybe, if NAMED on the names attribute is incremented, it can be caught.

[arunsrinivasan]

Updated SO links from above.