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/bottombuttongroup.cpp

@@ -21,11 +21,7 @@ BottomButtonGroup::BottomButtonGroup(const std::vector<QAction *> &actionList, Q
     this->setLayout(mainLayout);
     this->setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Minimum);
     this->setStyleSheet("BottomButtonGroup {"
-                        "border: 1px solid gray;"
-                        "border-top-left-radius: 10px;"
-                        "border-top-right-radius: 10px;"
                         "border-style: none;"
-                        "background-color:rgba(0,0,0,120)"
                         "}"
                         "QToolButton {"
                         "background:transparent;"
@@ -45,6 +41,7 @@ BottomButtonGroup::BottomButtonGroup(const std::vector<QAction *> &actionList, Q
     for (QAction * action : actionList) {
         addButton(newActionBtn(action));
     }
+
 }
 
 void BottomButtonGroup::setOpacity(qreal opacity, bool animated)