Refactored TTexture to allow encoding sprite(s) at an arbitrary location within a (possibly shared) physical texture. The original variant only allowed encoding a sprite at the bottomleft of a larger physical texture to use NPOT sprites on POT only supporting systems.

sky = 179, 243, 243
border = 128, 128, 128
water-top = $54, $5C, $9D
water-bottom = $34, $3C, $7D
water-opacity = $80
music = Nature.ogg
clouds = 0
flakes = 0, 0, 0, 0, 0