update docs and screenshots

Doku/gdb.tex

Doku/gnuplot.tex

Doku/gnuplot_plot.tex

Doku/screenshot/dia.jpg

Doku/screenshot/dia.png

Doku/screenshot/firefox.jpg

Doku/screenshot/firefox.png

Doku/screenshot/gufw.jpg

Doku/screenshot/gufw.png

Doku/screenshot/inkscape.jpg

Doku/screenshot/inkscape.png

Doku/screenshot/kile.png

Doku/screenshot/texstudio.jpg

Doku/screenshot/texstudio.png

Doku/screenshot/thunderbird.jpg

Doku/screenshot/thunderbird.png

Doku/thunderbird.tex

Doku/valgrind.tex

scripts/linuxparty.sh