Added 6d facedir to logs(only merge if #988 is merged)

Logs can now be place horizontally.   Holding shift while placing inverts the facedir:  eg. if you place it on a wall and hold shift, it will face upwards, and vice versa.  This will only work if #988 on minetest is merged.

![screenshot_864208727](https://f.cloud.github.com/assets/3642781/1493561/e1ae35ee-47ce-11e3-8294-ce9167365323.png)