Additional levels and player actions, and bugfixes.

With this update the game is more in line with what we wanted the result to be at the end of the game jam. The original versions are here for comparison.

Changes

• Players now have access to 5 actions instead of 3.
• Rebalanced the actions.
• Every 3 levels, there is now a shop level where players can choose to upgrade some actions.
  • This does not apply to all actions and the upgrade cost is related to its power.
  • The upgrades are paid for with the 'pips' currency, which they get after completing a level.
• Add some battle UI for clarity: block icon, energy text, health text.