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.

ui->clearButton->setIcon(platformStyle->SingleColorIcon(":/icons/remove"));
    ui->fontBiggerButton->setIcon(platformStyle->SingleColorIcon(":/icons/fontbigger"));
    ui->fontSmallerButton->setIcon(platformStyle->SingleColorIcon(":/icons/fontsmaller"));
    // 
    ui->lineEdit->installEventFilter(this);
    ui->messagesWidget->installEventFilter(this);
    connect(ui->clearButton, SIGNAL(clicked()), this, SLOT(clear()));
    connect(ui->fontBiggerButton, SIGNAL(clicked()), this, SLOT(fontBigger()));
    connect(ui->fontSmallerButton, SIGNAL(clicked()), this, SLOT(fontSmaller()));
    connect(ui->btnClearTrafficGraph, SIGNAL(clicked()), ui->trafficGraph, SLOT(clear()));
    // set library version labels
#ifdef ENABLE_WALLET
    ui->berkeleyDBVersion->setText(DbEnv::version(0, 0, 0));
#else
    ui->label_berkeleyDBVersion->hide();
    ui->berkeleyDBVersion->hide();
#endif
    // 
    rpcTimerInterface = new QtRPCTimerInterface();
    // 
    // 
    RPCSetTimerInterfaceIfUnset(rpcTimerInterface);
    setTrafficGraphRange(INITIAL_TRAFFIC_GRAPH_MINS);
    ui->detailWidget->hide();
    ui->peerHeading->setText(tr("Select a peer to view detailed information."));
    QSettings settings;
    consoleFontSize = settings.value(fontSizeSettingsKey, QFontInfo(QFont()).pointSize()).toInt();
    clear();
}
RPCConsole::~RPCConsole()