Update 0.3.377 - Some graphics tweaks

I'm quite busy working on campaign ideas so this update only brings a bunch of smaller changes. Have fun! :)

• Hex grid overlay is more subtle in appearance and it can be turned off from settings
• Desert tiles got smooth textures which makes the map a bit less noisy and makes it easier to tell the difference between the three soil types
• Terraformed hexes have a subtle random lightness value applied to them to break up their uniform appearance