20090511

merging many pdf files into one.

Given input files: 0001.pdf, 0002.pdf, 0003.pdf.
Output file: output.pdf
Requirements: GhostScript

gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=output.pdf -dBATCH 0001.pdf 0002.pdf 0003.pdf