issue_comments

@simonw What about allowing a base url. The <base>....</base> tag has been around forever. Then just use all relative URLs, which I guess is likely what you already do. See https://www.w3schools.com/TAGs/tag_base.asp

FWIW I did a dumb merge of the branch here: https://github.com/jsfenfen/datasette and it seemed to work in that I could run stuff at a subdirectory, but ended up abandoning it in favor of just posting a subdomain because getting the nginx configs right was making me crazy. I still would prefer posting at a subdirectory but the subdomain seems simpler at the moment.

Hmmm, wait, maybe my mindless (copy/paste) use of proxy_redirect is causing me grief...

Agreed, this would be nice to have. I'm currently working around it in nginx with additional location blocks:

```

location /datasette/ {
    proxy_pass         http://127.0.0.1:8001/;
    proxy_redirect     off;
    include proxy_params;
}

location /dna-protein-genome/ {
    proxy_pass         http://127.0.0.1:8001/dna-protein-genome/;
    proxy_redirect     off;
    include proxy_params;
}

location /rna-protein-genome/ {
    proxy_pass         http://127.0.0.1:8001/rna-protein-genome/;
    proxy_redirect     off;
    include proxy_params;
}

```

The 2nd and 3rd above are my databases. This works, but I have a small problem with URLs like /rna-protein-genome?params.... that I could fix with some more nginx munging. I seem to do this sort of thing once every 5 years and then have to look it all up again.

Thanks!