[Swan-dev] rename ip_subnet to ip_selector

[Andrew Cagney]

(or ip_filter)
Per comment in ip_subnet.h:

 * This is not the subnet you're looking for.
 *
 * In libreswan ip_subnet is used to store client routing information.
 * IKEv2 calls this traffic selectors and it allows the negotiation
 * of:
 *
 *    LO_ADDRESS..HI_ADDRESS : LO_PORT..HI_PORT
 *
 * The structures below can only handle a limited subset of this,
 * namely:
 *
 *    NETWORK_PREFIX | 0 / MASK : PORT
 *
 * where PORT==0 imples 0..65535, and (presumably) port can only be
 * non-zero when the NETWORK_PREFIX/MASK is for a single address.

since most code is using ip_subnet as a selector/filter.

We've then got space for an ip_subnet type.

Andrew