bug#8534: 24.0.50; Documentation bug in ns-read-file-name

[Harald Hanche-Olsen <hanche@math.ntnu.no>]

The doc string for ns-read-file-name (defined in src/nsfns.m) says

Optional arg ISLOAD, if non-nil, means read a file name for saving.

However the exact opposite is true, as the name of the variable also
indicates.

On a side note, when the function is called (with ISLOAD = nil) and
you select an existing file, the usual warning pane about overwriting
an existing file pops up briefly before the dialog vanishes and the
function returns the chosen filename. It is not clear to me if this is
the intended behaviour, but I find it confusing. It would have been
better, I think, to let the save dialog do its usual thing, and then
for the caller of ns-read-file-name to assume that the user has
authorized the overwriting of a pre-existing file with the same name.

In GNU Emacs 24.0.50.1 (x86_64-apple-darwin10.7.0, NS apple-appkit-1038.35)
 of 2011-04-21 on mack
Windowing system distributor `Apple', version 10.3.1038
configured using `configure  '--with-ns''

- Harald