* update from ionicons-npm to ionicons ver.5
* drop the webfont built by grunt for icons
* built icons.html template for inlining icons with jinja2 into html
* update icon to use mostly the outline version
* add icons to categories and do not display them on mobile to save space
* remove all legacy ion icon font files from simple theme
* icons.html is added in this commit since make statc.build.restore requires git to know the file already
* cleanup error-dialog
When an image is selected, the detail with the full size image is displayed
on the right side of the screen (or full screen on tablet and phone).
When Javascript is disabled, the thumbnail is a linked to the full size image,
as it was before.
When the image proxy is enabled, the full size image is also proxied,
in consequence this commit increases the bandwidth usage of instances.
The detail can be closed by the close button or the Esc key.
It is possible to go to the next and previous images using the j and k keys
or the button on the top right of the screen.
