Add navigation toolbar (#1)

* Add preferences view skeleton

* Add toolbar & help button

* Add working back button

* Title of page in toolbar

* Remove unused imports

* Make comments better!

* Remove unused drawer element

* Remove superfluous > 1 check

* Use point size font instead of pixel size

* Add AppView page title

app/gui/main.qml

@@ -1,5 +1,6 @@
 import QtQuick 2.9
 import QtQuick.Controls 2.2
+import QtQuick.Layouts 1.3
 
 ApplicationWindow {
     id: window
@@ -13,4 +14,60 @@ ApplicationWindow {
         initialItem: "PcView.qml"
         anchors.fill: parent
     }
+
+    header: ToolBar {
+
+        RowLayout {
+            spacing: 20
+            anchors.fill: parent
+
+            ToolButton {
+                // Only make the button visible if the user has navigated somewhere.
+                visible: stackView.depth > 1
+
+                icon.source: "qrc:/res/arrow_left.png"
+                onClicked: stackView.pop()
+
+                Menu {
+                    id: backButton
+                    x: parent.width - width
+                    transformOrigin: Menu.TopRight
+                }
+            }
+
+            Label {
+                id: titleLabel
+                text: stackView.currentItem.objectName
+                font.pointSize: 15
+                elide: Label.ElideRight
+                horizontalAlignment: Qt.AlignHCenter
+                verticalAlignment: Qt.AlignVCenter
+                Layout.fillWidth: true
+            }
+
+            ToolButton {
+                icon.source: "qrc:/res/settings.png"
+                onClicked: stackView.push("qrc:/gui/SettingsView.qml")
+
+                Menu {
+                    id: optionsMenu
+                    x: parent.width
+                    transformOrigin: Menu.TopRight
+                }
+            }
+
+            ToolButton {
+                icon.source: "qrc:/res/question_mark.png"
+
+                // TODO need to make sure browser is brought to foreground.
+                onClicked: Qt.openUrlExternally("https://github.com/moonlight-stream/moonlight-docs/wiki/Setup-Guide");
+
+                Menu {
+                    id: helpButton
+                    x: parent.width
+                    transformOrigin: Menu.TopRight
+                }
+            }
+        }
+    }
 }