Same same, but different. (See previous commit for details.)

o Human-readable format of authentication method in overview
o Refine behaviour of enable / apply on main IPsec page
o Dedup leftsubnet/rightsubnet for meshed IKEv2
o More elegant interface and service plugging
o Tunnel isolation mode for IKEv2 (unmashed)
o Cleanup pass over backend code
o Allow Camellia for IKEv2
o Allow %any in phase 1
o Allow EAP-MSCHAPV2