By default, vim seems to save a backup file ending in a tilde (see
:help backup). For example, when editing
foobar.txt, a backup file
foobar.txt~ is saved. I would like to have it saved to
.foobar.txt~ instead. On Linux, a file starting with a dot is considered a hidden file.
I can't use the option
backupext because it only allows use to set an extension and not a prefix.