### FEATURE REQUEST

Currently, when a bitcoin node is set up with a connection to both TOR and normal IPv4/6 internet, the 8 outbound-only connection slots, almost always get filled with nodes connecting over IP.
Adding a config option, which would try to ballance these connections based on what kind of network they go through, would be benefficial in many ways:

1. It would add edges between bitcoin network on TOR and normal internet, reducing delays, and the risks associated with an attacker isolating a part of TOR-bitcoin-network from the rest of the world
(Or an ISP/government man-in-the-middling all the normal IP connections)

2. It would help hide/annonymise normal user's transactions from his/her ISP, by mixing them with TOR-outbound ones

3. It would reduce the stress on normal general purpose TOR exit nodes, as users would more likely/reliably connect to TOR-IPv4/6 bitcoin nodes instead of exiting into normal internet first, and then connecting to default IPv4/6-only bitcoin nodes

I understand it is possible to create such bridges already, by forcing connections to TOR-only nodes, or by just running a node with lots of inbound slots, but I think the proposed option, would greatly increase the number of such relays, and remove the need for user to maintain a TOR-node whitelist, by handing this work off to normal bitcoind connection finding algorithm.

This could be implemented as a minimum number of connections for each network, or just a simple evening boolean switch. (Which could be enabled by default for bitcoind installs with TOR connectivity)

In the future, if bitcoin was to support a new network type (for example cjdns/I2P/GNUnet), this option would help establish a presence on the new network faster

bitcoind: 0.15
{
    CDataStream ssPeersIn(SER_DISK, CLIENT_VERSION);
    ssPeersIn << Params().MessageStart();
    ssPeersIn << _addrman;
    std::string str = ssPeersIn.str();
    std::vector<unsigned char> vchData(str.begin(), str.end());
    return CDataStream(vchData, SER_DISK, CLIENT_VERSION);
}
BOOST_FIXTURE_TEST_SUITE(net_tests, BasicTestingSetup)
BOOST_AUTO_TEST_CASE(cnode_listen_port)
{
    
    uint16_t port{GetListenPort()};
    BOOST_CHECK(port == Params().GetDefaultPort());
    
    uint16_t altPort = 12345;
    BOOST_CHECK(gArgs.SoftSetArg("-port", ToString(altPort)));
    port = GetListenPort();
    BOOST_CHECK(port == altPort);
}
BOOST_AUTO_TEST_CASE(caddrdb_read)
{
    CAddrManUncorrupted addrmanUncorrupted;
    addrmanUncorrupted.MakeDeterministic();
    CService addr1, addr2, addr3;
    BOOST_CHECK(Lookup("250.7.1.1", addr1, 8333, false));
    BOOST_CHECK(Lookup("250.7.2.2", addr2, 9999, false));
    BOOST_CHECK(Lookup("250.7.3.3", addr3, 9999, false));