This commit adds support for determining and tracking the type of a
network address when constructed.

This commit introduces a network address type filter that allows a
caller to indicate the types of addresses that can be returned from
the address manager.  This allows finer control of what types of
addresses may be broadcast to a particular peer.  The filters are
decided by the protocol version of the peer in a way that allows the
address manager's internal implementation to remain agnostic of the
protocol versioning logic.

This prevents sending addresses in a version message that cannot be
converted to a wire network address.

This removes the need to perform DNS lookups in the address manager.

This change adds support for TORv3 addresses to the address
manager.  It also allows connecting to a TORv3 hostname with the
cli --connect flag when starting dcrd.  It does not support relaying
TORv3 addresses over the peer to peer network.

This change removes support for the TORv2 network address
persistence and propogation across the peer to peer network.

This commit modifies the wire protocol by adding two new message
types addrv2 and getaddrv2 and bumps the wire protocol version to 10.
It does not introduce any new network address types and is intended
to implement the minimum framework necessary to support easily adding
new address types in future commits.

These two new message types are intended to eventually replace their
older counterparts, which are getaddr and addr respectively.  A peer
sending a getaddrv2 or addrv2 message with a protocol version less than
10 is in violation of the wire protocol and the peer is disconnected.
Similarly, peers advertising a protocol version greater than or equal
to 10 that send an addr or gettaddr message are in violation of the wire
protocol and are disconnected.

A getaddrv2 message is similar in structure and purpose to a getaddr
message in that it has no payload and functions as a request for a peer
to reply with an addrv2 message if it has addresses to share. An addrv2
message is similar in structure and function to an addr message
with a few key differences:

- Port is now encoded as a little endian value rather than big endian.
- Timestamp is encoded as a 64 bit value rather than a 32 bit value.
- A network address type field is now serialized with each address to
  indicate the length and type of the address it precedes.
- A message with zero addresses is no longer serializable.
- Addresses are serialized their most compact form, rather than
  always being encoded into a 16 byte structure.

This commit adds support for address types supported by the address
manager when recieving addresses from a seeder.

This commit relays TORv3 addresses across the peer to peer network and
bumps the wire protocol version to 11.