Move from SNOW to multicore package for parallel executions

[rbruggner]

Also, use mcmapply to iterate for all function arguments over clusters.

[rbruggner]

Actually, include snow. Use Snow to pass out each condition run to a new node. Once on the worker node, use mcapply to run the things that should parallelized locally on the worker node.

[rbruggner]

Fixed in 48c53ffc583da13f87e909de8764fa9cc83fb18e