Colour Balancing & Texture Changes (#314)

* Colour balancing / texture changes

Slight changes to block colours to look nicer.
- Oak leaves are darker than grass. Oak woods are less saturated
- Sand is darker and more yellow
- Stone and soil are both slightly lighter

Texture changes:
- Sand tiles better
- Gravel tiles better

* Cont. colour balancing and texture changes

Essentially a more polished version of last commit. 
Soil is more textured, with a new highlight colour
New log is higher contrast
New planks texture that is less contrasty

* New grass plant texture

* Edit sand.json to reflect texture changes

* Delete misplaced texture

* New grass plant texture

* Fix line endings

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Co-authored-by: IntegratedQuantum <jahe788@gmail.com>

assets/cubyz/blocks/sand.json

@@ -5,7 +5,5 @@
 		"auto"
 	],
 	"model" : "cube",
-	"texture_top" : "cubyz:sand",
-	"texture" : "cubyz:sand_side",
-	"texture_bottom" : "cubyz:sand"
+	"texture" : "cubyz:sand",
 }