Add a presencesensor interface

libnymea/interfaces/interfaces.qrc

@@ -60,6 +60,7 @@
         <file>extendedevcharger.json</file>
         <file>noisesensor.json</file>
         <file>co2sensor.json</file>
+        <file>presencesensor.json</file>
     </qresource>
     <qresource prefix="/"/>
 </RCC>

libnymea/interfaces/presencesensor.json

@@ -0,0 +1,15 @@
+{
+    "extends": "sensor",
+    "description": "The presence sensor interface provides information whether a certain thing, for instance a human person, a tracked animal, a tracked mobile phone or smart watch is currently present. Additionally it gives information about the last time the tracked thing has been seen.",
+    "states": [
+        {
+            "name": "isPresent",
+            "type": "bool"
+        },
+        {
+            "name": "lastSeenTime",
+            "type": "int",
+            "unit": "UnixTime"
+        }
+    ]
+}