ui: fix window issue introduced by QT 5.15.1. Investigate why this is required at all.

src/noggit/ui/DetailInfos.cpp

@@ -9,7 +9,7 @@ namespace noggit
   namespace ui
   {
     detail_infos::detail_infos(QWidget* parent)
-      : widget (parent)
+      : widget (parent, Qt::Window)
     {
       setWindowFlags (Qt::Tool);
       auto layout (new QFormLayout (this));

src/noggit/ui/Help.cpp

@@ -17,7 +17,7 @@ namespace noggit
   {
 
     help::help(QWidget* parent)
-      : widget (parent)
+      : widget (parent, Qt::Window)
     {
       setWindowTitle ("Help");
       setWindowIcon (QIcon (":/icon"));

src/noggit/ui/TexturePicker.cpp

@@ -22,7 +22,7 @@ namespace noggit
   {
     texture_picker::texture_picker
         (current_texture* current_texture_window, QWidget* parent)
-      : widget (parent)
+      : widget (parent, Qt::Window)
       , layout (new ::QGridLayout(this))
       , _chunk (nullptr)
     {