added option to set the number of threads
added option to set the number of threads

[git-p4: depot-paths = "//sw/gpgpu/nvbio/main/": change = 18537503]

NVlabs/nvbio,kimrutherford/nvbio,kimrutherford/nvbio,NVlabs/nvbio,kimrutherford/nvbio,NVlabs/nvbio,kimrutherford/nvbio,NVlabs/nvbio