Reduce doxygen footprint on debian

When you install doxygen on a recent debian OS, it will also install doxygen-latex, which bloats the footprint (on 32-bit wheezy) from 7.5 to 963 MB.
To avoid that once and for all, pin the doxygen-latex package with a negative priority, thereby preventing it from ever installing:

sudo sh -c 'cat > /etc/apt/preferences.d/doxygen-latex'
Package: doxygen-latex
Pin: version *
Pin-Priority: -1

To be precise, this trick lowers the requirement for doxygen from 633 MB download and 963 MB disk space down to 2.5 MB download and 7.5 MB disk space.