Make fastq_nuc_dist_graph.sh  DASH-compatible.
Make fastq_nuc_dist_graph.sh  DASH-compatible.

Things which works with 'bash' fails with 'dash'.
and DASH is the default shell in ubuntu/debian.

agordon/fastx_toolkit,agordon/fastx_toolkit,agordon/fastx_toolkit,agordon/fastx_toolkit