lynx-dev vote for EXP_PERSISTENT_COOKIES as default

[Leonid Pauzner]

I vote to made EXP_PERSISTENT_COOKIES symbol defined by default
unless otherwise specified or we are in anonymous mode.
It works stable (unless multiple lynxes started from the same account
and we may lost the last session cookies in a worst case).

Persistent cookies looks like great advantage over the previous release
but may be out if sysadm or a person who made a binary for distribution
read INSTALLATION file not very carefully.