3-thumbnail research note display inline in notes or wiki pages

[jywarren]

This'd be useful when displaying topically relevant notes inline in notes or wikis, like this:

The mobile view could look like the nytimes.com listing here:

However I think this could be doable as a variant of the [table-based display of inline grids, which is currently done here: https://github.com/publiclab/plots2/blob/master/app/helpers/application_helper.rb#L32-L58

You'd be able to insert them using an inline tag like [thumbnails:tagname] -- similarly as described here: https://publiclab.org/wiki/power-tags#Inline+power+tags

They look like this:

We'd just use a paginated 3-column display of these node templates: https://github.com/publiclab/plots2/blob/master/app/views/dashboard/_node_default.html.erb

The dashboard view at https://publiclab.org/research uses a 2-column version of this that could be copied:

https://github.com/publiclab/plots2/blob/master/app/views/dashboard/_activity.html.erb#L50-L64

[jywarren]

Merging into #1097.