Fertilizer highlight plot

[AaronLS]

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Since fertilization affects the plot, which isn't really explained anywhere in game. It'd be apparent if it highlighted the plot instead of a square when holding fertilizer in hotbar.

Also I'd suggest not using the same plot highlighting as with the stake. I get really disoriented when holding the stake because the green is very opaque and walls/floors don't look any different. Use alot more transparency, and only highlight the tops of blocks.