Tasks and evolutions management

Added a convenient task viewing system. Now only completed and available tasks are shown to the player. The player can receive rewards for completing tasks, such as evolution points.

These points are required for leveling evolution. By pumping evolutions, the player gets access to the construction of new organelles and one free organelle right there. You can see the available points in the evolution menu. (P.S. The spoiler for the upcoming additions is marked in green)

Also, the plot pages are now available sequentially according to the tasks performed.