Moved global variables into the "default" list/class.
Both furnaces moved to 'default/furnace.lua' with updated formspecs to keep Carbone's semi-transparent background.
Fixed: dereferencement of uninitialized global variable.
Removed garbage in 'bucket/init.lua'.
Removed temporay files.
Merge branch 'mgl512-devel'
tweak the description

Because before « leaves » and « jungle leaves » has the same name
« leaves », and players was unable to recognize which is exactly the
right « leaves » …