feat: rebalance building attributes (#157)

balance tavern

feat: new Island model & all 7 new Buildings including models (#156)

docs: add contribution

feat: add building Well

fix: description of building Market

feat: add building Tavern

feat: add building Market

feat: add building Lumbermill

feat: add building Blacksmith

docs: update the used assets & materials

fix: outline must contain all meshes of a model, not only leafs

feat: add building Windmill

feat: add building HomeA

feat: add model Buildings as scene with all buildings

feat: add new BuildArea model

feat: add new Island model

feat: new texture

feat: new model for BuildArea

chore: remove buildings Windmill & CarnationShop

feat: add gradient-based Sky Box for sky and ocean floor (#152)

feat: use new sky box with ocean floor instead of sky dome & ocean floor

feat: add sky box with ocean floor and all needed shaders

chore: ocean fog does not need an offset anymore

chore: remove sky dome

chore: remove ocean floor