feat: modify pienapple-picture with my remix

- change UI layout to make it looks like the default style of Windows image browser.
- update icons to material design icon for better looks. add lost icons for those new added button at the bottom bar.
- restore window style to normal. remove borderless style.
- delete X button at the right-top corner. disable feature that drag window to move, because all functions provided by native window are restored.
- move prev next image button to the center of bottom bar.
- move navigator view to the right-bottom corner so that it will not overlay on the shown image.
- remove all animation effect, including alpha transition, fade out when exiting and etc.
- delete function that double click windows to exit. now double clicking windows will do nothing. change default value of double click behavior to do nothing.
- change default value of stay on top to false because stay on top is not the default behavior of Windows image browser.

app/framelesswindow.h

@@ -16,22 +16,9 @@ class FramelessWindow : public QWidget
     Q_OBJECT
 public:
     explicit FramelessWindow(QWidget *parent = nullptr);
-
     void setCentralWidget(QWidget * widget);
-    void installResizeCapture(QObject* widget);
-
-protected:
-    bool eventFilter(QObject *o, QEvent *e) override;
-    bool mouseHover(QHoverEvent* event, QWidget* wg);
-    bool mousePress(QMouseEvent* event);
 
 private:
-    Qt::Edges m_oldEdges;
-    Qt::CursorShape m_oldCursorShape;
-
-    Qt::CursorShape getCursorByEdge(const Qt::Edges& edges, Qt::CursorShape default_cursor);
-    Qt::Edges getEdgesByPos(const QPoint pos, const QRect& winrect);
-
     QVBoxLayout * m_centralLayout = nullptr;
     QWidget * m_centralWidget = nullptr; // just a pointer, doesn't take the ownership.
 };