Copy data and metadata. Return the file's destination.
Metadata is copied with copystat(). Please see the copystat function
for more information.
The destination may be a directory.
If follow_symlinks is false, symlinks won't be followed. This
resembles GNU's "cp -P src dst".
3.3: Added follow_symlinks argument, try to copy extended file system attributes too (currently Linux only). Now returns path to the newly created file.
3.8: Platform-specific fast-copy syscalls may be used internally in order to copy the file more efficiently. See Platform-dependent efficient copy operations section.