Implementing weight of the player's character

[voxelproof]

I've noticed that stepping on an unsupported sand node doesn't make it fall. Wouldn't it be more resonable to make such movement have the same impact on fallable nodes as punching them?

The second proposal concernes snow. From my own experience I can say that walking in a 1-meter deep fresh snow isn't much faster than walking through water of the same depth. Maybe this goes too far, but I think that movement in snowy biomes should be a little slower.