Pine tree, pine needles, pine saplng and pine wood nodes, stairs and slabs

![screenshot_2024655708](https://cloud.githubusercontent.com/assets/3686677/4894770/d8b4efc8-63d9-11e4-8492-603c450b97fc.png)


Adds the remaining snow biome nodes from Splizard's snow mod: needles and pine sapling (with permission), plus my own pinetree and pinewood nodes and textures. The pine sapling does not grow into a pine yet, the ABM and pinetree design can be a later commit.
These nodes enable 2 new biomes temperate coniferous forest and taiga, the needles node can be used for many types of conifer, the golden wood planks are good for Scandinavian furniture.