Implements tree visibility occlusion system.

Adds tree fading based on camera line of sight.
Trees now fade out when they obstruct the player's view,
improving visibility.

Also includes several fixes:
- Fixes tree distribution.
- Adds a see-through shader.
- Adds camera and occlusion scripts.

Utilities/MapData/MapPopulation.gd

@@ -44,7 +44,7 @@ static func calculate_tree_distribution(tree_preferences: Dictionary, density: f
 		return distribution
 	
 	# Calculate total number of trees for this cell
-	var total_trees = int((density / 2) * 10) + randi_range(1, 3)
+	var total_trees = int((density / 5) * 10) + randi_range(1, 2)
 	#var total_trees = int((density - 0.6) * 25) + randi_range(3, 8)
 
 	# Normalize the chances to get proportions