Improved Ground Graphics

Arboreal Demigod updated to 0.5.1.

Changes:

• Shading on ground graphics has been improved. As the ground covers roughly a third of the screen most of the time, this brings a great improvement to the aesthetic of the game.
• When playing on the human level, an objective will now be randomly chosen of either "Number of ceremonies attended" or "Number of woodcutters absorbed".
• A message is now displayed on screen when the player has run out of energy and has tried to do actions that require it like moving and spawning trees.
•  I've found that crows have been getting population explosions too often, so crows now lay eggs slightly less often.