add impedances checks

Closes #254 (closed)

applications/openvibe-parameters-qml/BoolParameter.qml

@@ -47,14 +47,10 @@ Control {
         anchors.right: _control.right
         anchors.leftMargin: 16
 
+        checked: _control.param ? _control.param.value : false
         onToggled: {
             if (_control.param)
                 _control.param.value = _switch.checked ? 1 : 0
         }
     }
-
-    Component.onCompleted: {
-        if (_control.param)
-            _switch.checked = _control.param.value
-    }
 }