Fix a bug when trying to place snow on an unknown node.
Describe snow_cobble as Icy Snow, create crafting recipes for it

Snow blocks now drop itself not snow cobble, you need to craft it now
with ice blocks and default:snow. This makes it more plentiful then snow
blocks but a bit harder to create.
Update Readme.
Use default nodenames.
Mix up the crafts a bit for snow_cobble.

Don't have much ice? no problem! use more snow.
Make ice easier to dig with a pickaxe.
Call this Version 3.0