stop autocreating d-lines for throttle violations

This didn't work correctly for IPv6 or custom nets.
/UNDLINE IP can temporarily be used to reset the throttle.

irc/flatip/adhoc.go

@@ -0,0 +1,33 @@
+// Copyright 2020 Shivaram Lingamneni <slingamn@cs.stanford.edu>
+// Released under the MIT license
+
+package flatip
+
+// begin ad-hoc utilities
+
+// ParseToNormalizedNet attempts to interpret a string either as an IP
+// network in CIDR notation, returning an IPNet, or as an IP address,
+// returning an IPNet that contains only that address.
+func ParseToNormalizedNet(netstr string) (ipnet IPNet, err error) {
+	_, ipnet, err = ParseCIDR(netstr)
+	if err == nil {
+		return
+	}
+	ip, err := ParseIP(netstr)
+	if err == nil {
+		ipnet.IP = ip
+		ipnet.PrefixLen = 128
+	}
+	return
+}
+
+// IPInNets is a convenience function for testing whether an IP is contained
+// in any member of a slice of IPNet's.
+func IPInNets(addr IP, nets []IPNet) bool {
+	for _, net := range nets {
+		if net.Contains(addr) {
+			return true
+		}
+	}
+	return false
+}