Fixed 1.8 world item format reading.
Merge pull request #1575 from mc-server/1.8-Item

Fixed 1.8 world item format reading.
QtBiomeVisualiser: Generator uses all machine threads.

The previous limit of 1 thread was lifted, now the generator source runs on all CPU threads available.
Merge pull request #1576 from mc-server/QtBiomeVisualiserThreadedGen

QtBiomeVisualiser: Generator uses all machine threads.