Updates

session.pl
- Added settings for auto-saving, displaying a warning when restoring
isn't done automatically and displaying a notification when autosaving
is enabled
- motd is now only hooked when restoring a session
- Nick changing is only hooked when the option is enabled

whois-on-pm.pl
- Added option to delay messages from showing up so that the whois
messages can be displayed first
- Added option to chose which messages to display

Changes to other scripts ensure that the variables closer to the top,
after use statements and before Xchat::register.

Finally, the format of the readme has also been updated.