grid.py : python program to generate grid files
	uses sherpa under ciao ver 4.3
	e.g. this will generate a grid file in the fits format (output.qgrid.fits) 
		and sherpa script used to calculate grid for reference (sherpa_grid.sph).

	grid.py \
	        --rmf=example.rmf \
	        --arf=example.arf \
	        --fits=output.qgrid.fits \
	        --model="xsphabs.A*xspowerlaw.B" \
	        --par1=A.nH:0.01,0.1,0.4,1,4,10:200 \
	        --par2=B.PhoIndex:0,1,2,3,4:200 \
	        --etcp=B.norm:1.0 
	        --range=0.3,8.0

example.pro : an idl program to plot grids
	using qdplot2.pro (warning: not polished yet)