[ANN] packetgen 3.1.4 released

packetgen 3.1.4 has been released.

* home: <https://github.com/sdaubert/packetgen>
* bugs: <https://github.com/sdaubert/packetgen/issues>
* doc: <https://github.com/sdaubert/packetgen/wiki>

PacketGen provides simple ways to generate, send and capture network
packets.

Supported protocols are: Ethernet, Dot11, Dot1x, ARP, IP, IPv6, GRE,
ICMP, IGMP, ICMPv6, MLD, MLDv2, OSPFv2, OSPFv3, UDP, TCP, SNMP, DNS,
EAP, BOOTP, DHCP, TFTP, HTTP and MDNS.

Changes:

### 3.1.4 / 2020-03-22

* Finally add a Changelog.
* Make some little speed improvement on Headerable#read, Packet#add,
Packet#insert and PcapNG::File#array_to_file.
* Clean up PcapNG module and Packet class.
* Drop Ruby 2.3 support on travis CI.
* Clean up gemspec.
* Types::AbstractTLV: add header_in_length flag. If set to true, then
length in computed not only on value field but also on type and length ones.
* Inspect module: add some helper methods.
* Add Header::Eth::MacAddr#==, Header::IP:Addr#== and Header::IPv6:Addr#==.
* Isolate dependency on PCAPRUB into PCAPRUBWrapper module.
* Add Inject module to factorize code to inject data on wire.
* Move pcap-read logic into new Pcap module.
* Add BindingError exception. This one replaces ArgumentError when no
binding is found between two headers.