Added block metadata support for storing 'unnatural' blocks.

After seeing a player use an exploit on my server, I decided to create a fix for it. Blocks moved by stick pistons are not treat as 'unnatural' and still give experience and a chance for double drops and loot.

This adds a metadata value called mc_bin and if set to any value when BlockCheck is called, returns straight away.

Previous pull request didn't give experience on natural blocks, this has been fixed.