Improved furnaces

* Fixed progress bar on 1.8
* Fixed bugs
* Improved code
* Fixes #1068
* Fixes #1070
Won't work for a furnace block with a (wrong) chest entity attached to it.

I was thinking more about cBlockEntity::CanBeAtBlock(BLOCKTYPE)
-- 
Sent from my Android phone with K-9 Mail. Please excuse my brevity.