Small code style issues

Contributes to issue CURA-5035.

plugins/Toolbox/resources/qml/ToolboxInstalledTile.qml

@@ -75,7 +75,7 @@ Item
             {
                 if (model.author_email)
                 {
-                    return "<a href=\"mailto:"+model.author_email+"?Subject=Cura: "+model.name+"\">"+model.author_name+"</a>"
+                    return "<a href=\"mailto:" + model.author_email + "?Subject=Cura: " + model.name + "\">" + model.author_name + "</a>"
                 }
                 else
                 {
@@ -87,7 +87,7 @@ Item
             wrapMode: Text.WordWrap
             verticalAlignment: Text.AlignVCenter
             horizontalAlignment: Text.AlignLeft
-            onLinkActivated: Qt.openUrlExternally("mailto:"+model.author_email+"?Subject=Cura: "+model.name+" Plugin")
+            onLinkActivated: Qt.openUrlExternally("mailto:" + model.author_email + "?Subject=Cura: " + model.name + " Plugin")
             color: model.enabled ? UM.Theme.getColor("text") : UM.Theme.getColor("lining")
         }
     }

plugins/Toolbox/resources/qml/ToolboxTabButton.qml

@@ -30,11 +30,11 @@ Button
             text: control.text
             color:
             {
-                if( control.hovered )
+                if(control.hovered)
                 {
                     return UM.Theme.getColor("topbar_button_text_hovered");
                 }
-                if( control.active )
+                if(control.active)
                 {
                     return UM.Theme.getColor("topbar_button_text_active");
                 }