Changes to desktop.el and misc.texi

[Lars Hansen]

I have made some changes to the desktop module and the documentation of 
it in the manual, and you may have comments to these changes.

Do you want to see diffs (rather large!) before I install, or should I 
just install and let you comment afterwards?

A brief description of the changes:

* desktop.el: A lot of comments updated.
(desktop-save-mode): Minor mode introduced.
(desktop-enable, desktop-clear-preserve-buffers): Variables made obsolete.
(desktop-load-default): Function made obsolete.
(desktop-locals-to-save): Variable made customizable.
(desktop-read): Optional parameter `dirname' added.
(desktop-change-dir, desktop-revert): Parameter `dirname' in 
`desktop-read' used.
(desktop-save-in-load-dir): Renamed to `desktop-save-in-desktop-dir'.

* misc.texi: Section "Saving Emacs Sessions" rewritten.