REFACTOR to be more modular

controllers/gui_controller.py

@@ -0,0 +1,9 @@
+from render.gui_renderer import GUIRenderer
+
+class GUIController:
+    def __init__(self, gui_renderer: GUIRenderer):
+        self.gui_renderer = gui_renderer
+        self.slider =  gui_renderer.slider
+
+    def update(self, event):
+        self.slider.handle_event(event)