Added Stairs + Added Decorations Creative Tab

-This way of declaring stairs makes it so that you can add any type of
block as a stair…
(Doesn’t have to be a declared tree block as logs, leaves and planks do)

- Added Decoration Creative tab for decoration blocks… We’re going to
have a lot of blocks… One tab for all block isn’t really organized…

Note: There isn’t that much block in the decoration tab as we don’t
have a lot blocks to put in… Yet…