pic: compressed images with pngcrush -brute

Done thusly:

    mkdir b
    cd b
    for f in ../*.png; do echo pngcrush -brute "$f" $(basename "$f"); done

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
all.tex: fixed typos in first two chapters

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>