Since 60befa399 in #9441, `bip68-sequence.py` (one of the extended rpc tests, not run by travis) has been failing:

```
Initializing test directory /var/folders/pw/k25spdv971g8xhccyx5t3yyr0000gn/T/test5y497icn/9191
Running test disable flag
Running test sequence-lock-confirmed-inputs
Running test sequence-lock-unconfirmed-inputs
Running test BIP68 not consensus before versionbits activation
Verifying nVersion=2 transactions aren't standard
Activating BIP68 (and 112/113)
Assertion failed: Block sync to height 432 timed out:
  {'hash': '05c02af44675851560cb13b1b59f2a7f08ff3bef4e3db19f6a08e79cb51cce62', 'height': 432}
  {'hash': '30f24ff219ac23291d1489710ad467726b7ab202f70923d4bd5707dacfb05051', 'height': 328}
  File "/Users/sdaftuar/projects/ccl-bitcoin/qa/rpc-tests/test_framework/test_framework.py", line 145, in main
    self.run_test()
  File "./bip68-sequence.py", line 58, in run_test
    self.activateCSV()
  File "./bip68-sequence.py", line 409, in activateCSV
    sync_blocks(self.nodes)
  File "/Users/sdaftuar/projects/ccl-bitcoin/qa/rpc-tests/test_framework/util.py", line 147, in sync_blocks
    maxheight, "".join("\n  {!r}".format(tip) for tip in tips)))
Stopping nodes
Not cleaning up dir /var/folders/pw/k25spdv971g8xhccyx5t3yyr0000gn/T/test5y497icn/9191
Failed
```

I git bisected the problem back to the above commit; the issue seems to be that the inactivity checking at https://github.com/theuni/bitcoin/blob/60befa3997b98d3f913010f2621bec734f643526/src/net.cpp#L1298 is comparing times that are coming from two different places: `GetTime()` which can use mocktime, and `GetTimeMicros()` which does not, and the `bip68-sequence.py` test uses mocktime.  (Using `GetTimeMicros()` for `nLastRecv` is newly introduced in the commit above.)

Really, it's sort of remarkable/lucky that we didn't have test failures relating to how mocktime interacts with the networking code before.  I'm not sure what the right way to fix this is -- I started by trying to narrowly just fix this issue by changing `nTimeConnected`, `nLastSend`, and the starting `nTime` used in the inactivity check to all be based off system clock (eg `GetTimeMicros()/1000000`), but then that broke some of our other tests that I think must have been relying on mocktime having an effect on some of these things (`maxuploadtarget.py`, `receivedby.py`, and `listtransactions.py` all failed -- I didn't investigate exactly what happened so it's possible my fix just had a simple mistake).

Anyway I think we need a thoughtful approach to how to use `GetTime()` vs. `GetTimeMicros()` for the various times we have, especially in `net.cpp`/`net_processing.cpp`, and this is a bug that I think we need to fix for 0.14 so we're not shipping broken tests.

* and is thus planned to be deprecated eventually.
 *
 * Based on the source of the information, new information should be added to:
 * - `getblockchaininfo`,
 * - `getnetworkinfo` or
 * - `getwalletinfo`
 *
 * Or alternatively, create a specific query method for the information.
 **/
UniValue getinfo(const JSONRPCRequest& request)
{
    if (request.fHelp || request.params.size() != 0)
        throw runtime_error(
            "getinfo\n"
            "\nDEPRECATED. Returns an object containing various state info.\n"
            "\nResult:\n"
            "{\n"
            "  \"version\": xxxxx,           (numeric) the server version\n"
            "  \"protocolversion\": xxxxx,   (numeric) the protocol version\n"
            "  \"walletversion\": xxxxx,     (numeric) the wallet version\n"
            "  \"balance\": xxxxxxx,         (numeric) the total bitcoin balance of the wallet\n"
            "  \"blocks\": xxxxxx,           (numeric) the current number of blocks processed in the server\n"
            "  \"timeoffset\": xxxxx,        (numeric) the time offset\n"
            "  \"connections\": xxxxx,       (numeric) the number of connections\n"
            "  \"proxy\": \"host:port\",     (string, optional) the proxy used by the server\n"
            "  \"difficulty\": xxxxxx,       (numeric) the current difficulty\n"
            "  \"testnet\": true|false,      (boolean) if the server is using testnet or not\n"
            "  \"keypoololdest\": xxxxxx,    (numeric) the timestamp (seconds since Unix epoch) of the oldest pre-generated key in the key pool\n"
            "  \"keypoolsize\": xxxx,        (numeric) how many new keys are pre-generated\n"
            "  \"unlocked_until\": ttt,      (numeric) the timestamp in seconds since epoch (midnight Jan 1 1970 GMT) that the wallet is unlocked for transfers, or 0 if the wallet is locked\n"