Parse argument of 'set_number_of_threads' as signed rather than unsigned int so that attempts to set negative numbers of threads can be caught and handled properly.
Parse argument of 'set_number_of_threads' as signed rather than unsigned int so that attempts to set negative numbers of threads can be caught and handled properly.

jas14/khmer,F1000Research/khmer,F1000Research/khmer,souravsingh/khmer,ged-lab/khmer,ged-lab/khmer,F1000Research/khmer,kdmurray91/khmer,souravsingh/khmer,kdmurray91/khmer,Winterflower/khmer,Winterflower/khmer,jas14/khmer,ged-lab/khmer,kdmurray91/khmer,Winterflower/khmer,souravsingh/khmer,jas14/khmer