Feature coke

Added coal coke along with a coal coke block. 

Coal coke is only available from the creative menus but can be crafted into a block. Both are fuels but the burn time needs to be changed ideally. 

For now the burn times are 5 minutes and 10 minutes respectively.

Textures need to be improved for sure but they work for now.

What do you think @Hanse00?