Add quit cli command and app quit option after stream session. Fixes #92 (#138)

* Add quit cli command and app quit option after stream session. Fixes #92

* Code review fixes.

app/backend/computerseeker.cpp

@@ -0,0 +1,59 @@
+#include "computerseeker.h"
+#include "computermanager.h"
+#include <QTimer>
+
+ComputerSeeker::ComputerSeeker(ComputerManager *manager, QString computerName, QObject *parent)
+    : QObject(parent), m_ComputerManager(manager), m_ComputerName(computerName),
+      m_TimeoutTimer(new QTimer(this))
+{
+    m_TimeoutTimer->setSingleShot(true);
+    connect(m_TimeoutTimer, &QTimer::timeout,
+            this, &ComputerSeeker::onTimeout);
+    connect(m_ComputerManager, &ComputerManager::computerStateChanged,
+            this, &ComputerSeeker::onComputerUpdated);
+}
+
+void ComputerSeeker::start(int timeout)
+{
+    m_TimeoutTimer->start(timeout);
+    // Seek desired computer by both connecting to it directly (this may fail
+    // if m_ComputerName is UUID, or the name that doesn't resolve to an IP
+    // address) and by polling it using mDNS, hopefully one of these methods
+    // would find the host
+    m_ComputerManager->addNewHost(m_ComputerName, false);
+    m_ComputerManager->startPolling();
+}
+
+void ComputerSeeker::onComputerUpdated(NvComputer *computer)
+{
+    if (!m_TimeoutTimer->isActive()) {
+        return;
+    }
+    if (matchComputer(computer) && isOnline(computer)) {
+        m_ComputerManager->stopPollingAsync();
+        m_TimeoutTimer->stop();
+        emit computerFound(computer);
+    }
+}
+
+bool ComputerSeeker::matchComputer(NvComputer *computer) const
+{
+    QString value = m_ComputerName.toLower();
+    return computer->name.toLower() == value ||
+           computer->localAddress.toLower() == value ||
+           computer->remoteAddress.toLower() == value ||
+           computer->manualAddress.toLower() == value ||
+           computer->uuid.toLower() == value;
+}
+
+bool ComputerSeeker::isOnline(NvComputer *computer) const
+{
+    return computer->state == NvComputer::CS_ONLINE;
+}
+
+void ComputerSeeker::onTimeout()
+{
+    m_TimeoutTimer->stop();
+    m_ComputerManager->stopPollingAsync();
+    emit errorTimeout();
+}