QtBiomeVisualiser: Added multithreading.

For some reason this makes the UI less responsive.
QtBiomeVisualiser: removed multithreading.

It was slowing things down, the granularity is too fine.
QtBiomeVisualiser: Added reloading.
QtBiomeVisualiser: Fixed colors and read failures.
VoronoiMap: Added Jitter and OddRowOffset params.