Move UI folder

UI/UI_button.cpp

@@ -0,0 +1,27 @@
+#include "UI_button.hpp"
+
+UI_button::UI_button(std::string text, Color fg_color, Color bg_color, QObject *parent)
+    : UI_item(UI_BUTTON_TYPE, text, 12, fg_color, bg_color, parent)
+{
+}
+
+UI_button::UI_button(const json &j, QObject *parent) : UI_item(UI_BUTTON_TYPE, parent)
+{
+    from_json(j);
+}
+
+void UI_button::from_json(const json &j)
+{
+    UI_item::from_json(j);
+}
+
+json UI_button::to_json(size_t id) const
+{
+    json j = UI_item::to_json(id);
+    return j;
+}
+
+void UI_button::click()
+{
+    emit on_click();
+}