Spring Theme

[SirFancyBacon]

Adds a Spring seasonal theme.
Makes the Twin Trees pink like Cherry Blossom trees
Makes Magic Trees Purple like Jacaranda trees

Themes compared:
Spring, Summer, Autumn, Winter

[SirFancyBacon]

Hold until after #969 to allow for tweaking after it's merger.
i think that the current brightness for when the ground is blended should be the brightness of the tiles once 969 is merged. Helps differentiate it from Summer and it will add to the over all whimsical look.