A complete rewrite of the gallery plugin:
* Using flexbox
* Using lightweight JS for lightbox to avoid anchor links, and allow full rotation
* Add slideshow as an additional field
* Make many more things configurable
* Better support for dirs, allow mixed paths
* Translatable captions for many files using metadata files
* SCSS instead of CSS
Reviewed-on: #1
Co-authored-by: Max Mehl <mail@mehl.mx>
Co-committed-by: Max Mehl <mail@mehl.mx>
