Always use INTERNAL_IP4_ADDRESS as "gateway" on Windows
It appears that Windows's 'netsh' utility doesn't like the VPN interface having a "gateway" address of 0.0.0.1, which is what vpnc-script-win.js would attempt to use if INTERNAL_IP4_NETMASK is /0. See openconnect!306 (comment 745139972).
As noted in the OpenConnect source, "It's a tunnel; having a gateway is meaningless."
Setting the "gateway" address for Windows to match INTERNAL_IP4_ADDRESS seems like the simplest way to make 'netsh' configure routingly correctly in all cases, including when the INTERNAL_IP4_NETMASK is either /0 or /32.
Should fix #30 (closed) (confirmed, thanks @DimitriPapadopoulos)