refactor of dx_spans_to_bed to handle complex tables
refactor of dx_spans_to_bed to handle complex tables

johnwallace123/dx-toolkit,jhuttner/dx-toolkit,dnanexus/dx-toolkit,olegnev/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,olegnev/dx-toolkit,andyshinn/dx-toolkit,olegnev/dx-toolkit,dnanexus/dx-toolkit,andyshinn/dx-toolkit,dnanexus/dx-toolkit,olegnev/dx-toolkit,johnwallace123/dx-toolkit,andyshinn/dx-toolkit,jhuttner/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,johnwallace123/dx-toolkit,andyshinn/dx-toolkit,olegnev/dx-toolkit,dnanexus/dx-toolkit,jhuttner/dx-toolkit,jhuttner/dx-toolkit,jhuttner/dx-toolkit,dnanexus/dx-toolkit,andyshinn/dx-toolkit,dnanexus/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,andyshinn/dx-toolkit,olegnev/dx-toolkit,olegnev/dx-toolkit,jhuttner/dx-toolkit,andyshinn/dx-toolkit,johnwallace123/dx-toolkit,olegnev/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,andyshinn/dx-toolkit