refactor: use UI file for main window

- main window now use UI file for layout.
- remove all manual computed widget position code. use full Qt layout implementation instead.
- remove useless functions in main window
- change style changed slot as private

app/bottombuttongroup.cpp

@@ -8,7 +8,7 @@
 #include <QVBoxLayout>
 #include <QDebug>
 
-BottomButtonGroup::BottomButtonGroup(const std::vector<QAction *> &actionList, QWidget *parent)
+BottomButtonGroup::BottomButtonGroup(QWidget *parent)
     : QGroupBox (parent)
 {
     QHBoxLayout * mainLayout = new QHBoxLayout(this);
@@ -25,7 +25,9 @@ QToolButton {
     border-style: none;
 }
 )#");
+}
 
+void BottomButtonGroup::addActions(const std::vector<QAction *> & actionList) {
     for (QAction * action : actionList) {
         // Create button
         QToolButton * btn = new QToolButton(this);
@@ -37,3 +39,7 @@ QToolButton {
     }
     updateGeometry();
 }
+
+void BottomButtonGroup::addAction(QAction* action) {
+    addActions({action});
+}