Make line splitting fail-safe

The userhost Irssi uses for line splitting can in some cases be wrong,
for instance when a proxy is used or when a server cloaks the hostname
without telling the client. Now Irssi always assumes the userhost is of
maximum length. 10 for username (common value) and 63 for hostname (in
RFC 2812).
irc_server_send_away: don't send empty param if there's no away reason
source cleanup: remove trailing whitespaces
Merge pull request #144 from jubalh/master

source cleanup: remove trailing whitespaces
Fix use-after-free bug with cached settings values

This patch fixes a couple of use-after-free bugs when caching various
string related setting values.

Fixes: #143
Merge pull request #142 from dequis/away-with-no-reason

irc_server_send_away: don't send empty param if there's no away reason
Merge pull request #140 from sebth/master

Make line splitting fail-safe
Merge pull request #147 from ahf/bugfix-143

Fix use-after-free bug with cached settings values
Prepare for 0.8.17
HEAD's now 0.8.18-head.
Remove unnecessary NULL check

Fixes: #135
Add header for v0.8.18-head
Disable SSLv3
Add NEWS entry on SSLv3
Tiny fix to the param order in the /SERVER REMOVE help
Merge pull request #153 from dequis/help-server-remove-fix

Tiny fix to the param order in the /SERVER REMOVE help
Actually fix the params for /SERVER REMOVE
Merge pull request #155 from dgl/server-remove

Actually fix the params for /SERVER REMOVE
Remove duplicate example from ignore.in

Duplicated line inserted in commit 66f5fb6. Reported by @sharethebug on IRC.
Merge pull request #163 from lewellyn/patch-1

Remove duplicate example from ignore.in