Parallelize search

[rvosa]

As per @rmounce's blog post: http://rossmounce.co.uk/2012/07/14/running-tnt-in-parallel/

[rvosa]

As per commit 0b7bb43 we now use a wrapper script that invokes 'ptnt' commands, whether these play nice with the underlying PVM installation (installed with yum on T7600) remains to be seen.