fileserver: grid view - preview img src attribute is not URL query-escaped about caddy

[mholt]

Thanks! Fixed.

[DenebTM]

Oh nice, that was fast! Two things though.

1. A literal % needs to be encoded as %25, else any filename containing a percent followed by hexadecimal digits will break. And although it doesn't seem to be an issue, & should be encoded as %26 for completeness' sake.

2. Tbh I was kind of anticipating less of a "quick and dirty" fix than my own lol. It seems to me that a custom function wrapping Go's url.PathEscape should be added to the template module, since the closest built-in function urlquery from text/templates isn't quite suitable for escaping paths.

[mholt]

I actually thought the html template action would escape accordingly based on context, but I guess that doesn't work.

I didn't reference any other implemention, only just now saw that you pushed some of your own commit elsewhere.