I keep working on bugs!

• Lumberjacks/Engineers should no longer circle in the middle of the map: this happened if they had targeted an unreachable tree. Trees will no longer spawn in unreachable areas of the map.
• Flowered trees no longer absorb melted fertilizer.
• Mega Colonist no longer prevent from unlocking the "No Workers" challenge.
• "Standard Tree Only" challenge, can no longer be unlocked if the fir trees are enabled.
• Fixed a mistake in the tutorial regarding chopping trees.
• Added "s" for seconds, in the Rain Collector Duration upgrade.

I'm still working on the stuttering issue. For now the work around is to exit and launch the game.