'cause it makes more sense. also, this action made me realize that
my website is very poorly designed, because to just rename one page
i needed to make changes in 6 different files! that's really gross...
i hope i can improve it.

i hope it will finally work...

git post-receive hook is the same, but jekyll now shouldn't purge all
generated thumbnails.

post-receive git hook is also tweaked. since thumbnails aren't needed on
site build time, they can be created after by copying `thumbs.sh` script
into site art directory, running it and deleting afterwards.

`hooks/post-receive`
```

{
    cp "$TMP_GIT_CLONE/art/thumbs.sh" "$PUBLIC_WWW/art/thumbs.sh"
    cd "$PUBLIC_WWW/art"
    sh thumbs.sh
    rm thumbs.sh
}

```

thumbnails are currently created using shell script and require
imagemagick installed on the server. i know it's stupid, but i think
that including thumbnails to repo is also stupid.

maybe later i replace this script with actual jekyll plugin, but for
this i'll need to familiarize myself with ruby.
but now i use following addition to the git hook on the server:

```
[ -f "$TMP_GIT_CLONE/art/thumbs.sh" ] && {
    dir="$PWD"
    cd "$TMP_GIT_CLONE/art/" && sh thumbs.sh && cd "$dir"
}
```

it happens after cloning to remote repo and before building with bundle.

overall, this is a bodge now, it recompiles all thumbnails every time
due to quirks in my current setup.