Iterate on graphics design

Improve the design, materials and lighting of the bottles and switch
arround the purple and yellow shape.

render.py

@@ -22,8 +22,8 @@ bottles = [
     ["Green", "Cube", "//src/graphics/green.png"],
     ["Black", "Spiked", "//src/graphics/black.png"],
     ["Cyan", "Sphere", "//src/graphics/cyan.png"],
-    ["Purple", "Cylinder", "//src/graphics/purple.png"],
+    ["Purple", "Pentagon", "//src/graphics/purple.png"],
-    ["Yellow", "Hexagon", "//src/graphics/yellow.png"],
+    ["Yellow", "Cylinder", "//src/graphics/yellow.png"],
     ["White", "Tubes", "//src/graphics/white.png"],
 ]