Added 'on the go' smelting

You can now smelt any smelt-able vanilla item except Lapis ore, cactus
and wood.
Only Smelts with coal currently.
Only one smelting operation per coal.
Added lapis, wood and cactus smelting
Some general code tidy-up and description update.
Fixed a spelling mistake
Update README.md
Merge pull request #1 from StoneWaves/master

Update the Development branch