Optimize pictures with optipng, jpegoptim and scour

About 356 kiB of savings, so no big improvement.

Just ran
```
function optALLthings() {
cd $1;
optipng -o9 *.png;
jpegoptim --strip-all *.jpg;
for img in `ls *.svg`;
do
    mv $img $img.tmp;
    scour.py -i $img.tmp -o $img --create-groups --enable-id-stripping --enable-comment-stripping --shorten-ids --remove-metadata;
done;
rm *.tmp;
for dir in `ls -d */`;
do
    optALLthings $dir;
    cd ..;
done;
}
```
in my apps directory.

Also fixed some file permissions with that (they shouldn't be executable, should they …).