include ifconfig_ environment variables in --up-restart env set

include ifconfig_ environment variables in --up-restart env set

here's my patch for bug #93: missing ifconfig_* env vars after
up-restart. Tested with both IPv4, IPv6, topology subnet and topology net30

Document differences between --up-restart and --up in openvpn.8

See trac #93 and the discussion starting with <555BF270.3090706@nikhef.nl>
on the openvpn-devel mailing list.

fix trac #93

Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <555BF270.3090706@nikhef.nl>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9705
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit db950be85d37eab40d8fffe0bc2060059f8a7e10)