Qml App add option to control DHT behaviour

As bitDHT is very noisy and keeps the radio always on on mobile thus
having huge impact on the battery life, DHT is now turned on only when
the App is interacting with the user byt default, on the option tab it
is possible to change this behaviour to set it always off, always on or
active depending on user interaction.
To handle settings AppSettings singleton has been added and a button on
the sidebar to edit configurations too

retroshare-qml-app/src/components/SideBar.qml

@@ -214,6 +214,10 @@ Drawer
 								platformGW.shareUrl(nodeUrl);
 							})
 					},
+					"Options": function()
+					{
+						stackView.push("qrc:/Options.qml")
+					},
 					"Terminate Core": function()
 					{
 						rsApi.request("/control/shutdown");
@@ -245,12 +249,17 @@ Drawer
 					icon: "/icons/share.svg"
 				}
 				ListElement
+				{
+					title: "Options"
+					showOnOsAndroid: false
+					icon: "/icons/options.svg"
+				}
+				ListElement
 				{
 					title: "Terminate Core"
 					showOnOsAndroid: false
 					icon: "/icons/exit.svg"
 				}
-
 			}
 
 			ScrollIndicator.vertical: ScrollIndicator { }