refact(engine_core.version): return both versions

required by engine#110

src/serverfunctions.liq

@@ -63,12 +63,15 @@ server.register(namespace="aura_engine",
 
 # Get version
 server.register(namespace="aura_engine",
-    description="Return the version of Engine Core",
+    description="Return the version of Engine Core and Liquidsoap",
     usage="version",
     "version",
     fun (s) -> begin
         ignore(s)
-        engine_version
+        json_data = json()
+        json_data.add("core", engine_version)
+        json_data.add("liquidsoap", liquidsoap.version)
+        json.stringify(json_data)
     end
 )