Added score history:

- The Player class now includes a List<Integer> that stores historical score modifications.
- Player cards now display the last 5 historical modifications.
- Player cards now have a 1dp wide grey border when not selected.
- Replaced the 9-patch images used for the card background/border with xml shapes.
- Modified the theme used by the main activity theme to prevent overdraw.
- Removed some redundant dimension resources.