====== Hints ======
===== pdfcrop input.pdf output.pdf =====
Modify pdf files created by ROOT to remove Rotate syntax.\\
Useful also in some latex inputs, in which pdfdriver doesn't support Rotate syntax.
===== pdfseparate input.pdf output_%04d.pdf =====
Separate each page into output_0001.pdf, output_0002.pdf, ...
===== pdfxup -x 4 -y 3 -o output.pdf input.pdf =====
Create an nup pdf file.