Copy files more easily by dired and tramp

Mark one src file in Dired buffer A, and
mark one dest dir in Dired buffer B. Then
type "c" in any dired buffer, and the file
will be copied. Since Dired supports tramp,
This makes copy much more convenient for small
files.

For large files, emacs seems hang......

Use .authinfo.gpg to save password, together with
.ssh/config to save node information in order to
access remote machines.