Only send SNI if the host name is not an IP address

* gnutls.c (gnutls_ip_address_p): New function.
(Fgnutls_boot): Only send SNI if the host name is not an IP address.
* net/shr.el (shr-make-table-1): dom.el changes for table rendering.
Better display for `paranoid' `network-security-level'

* net/nsm.el (nsm-new-fingerprint-ok-p): Display the certificate
when querying about new certificates.