[WIP: missing values] Add BlastResistance to Material

For my explosion implementation I need to know the block's blast resistance. Since it depends on the Material, I thought it could be simple added to the existing Material enum.
The current solution is not as nice as a constructor argument would be, but IMO there's no other way.

Please leave feedback, then I'll add the rest blast resistance values, but maybe someone as another / better idea how to that?