Do not compile the final exam manually with pdflatex (Feature #404)

Hello,

I just wanted to share this tiny issue I had recently. May be you could add a warning in the documentation.

When I printed the final exam for the students, I compiled it manually with pdflatex without realising that this results in a slightly different PDF file where, in particular, the horizontal check boxes used for marking open questions are spaced differently from the file generated by AMC. This prevents AMC from detect the boxes on the scanned exams. In my case, I fixed the problem by editing the DOC-calage.xy file but it is quite a cumbersome process...
Digging into the code, I found that the actual command used to compile the exam copies within AMC is something like

pdflatex --jobname=amc-compiled '\nonstopmode\def\NoWatermarkExterne{1}\def\NoHyperRef{1}\def\SujetExterne{1} \input{"exam.tex"}'