Add thumbnail view for folder list admin view (updated)

[corentinbettiol]

Hi :)

Since it's way more easier to manage images in django-filer with bigger thumbnails instead of the small ones we have in the list, I wanted to add a thumbnail view.

This PR aims to solve #723.

I saw that the PR #1076 already included all the required changes, but for an unknown reason wasn't merged back in 2018. So I cherry-picked the commits and backported them onto the master branch on our fork :)

Here's a demo video (feature is shown at ~ 15 seconds) − And here's a more recent screenshot.

[jrief]

@corentinbettiol This looks great! I hope that it doesn't create too many conflicts with the pull request adding SVG icons and support in general.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[corentinbettiol]

Hi @jrief, sorry for pinging you like this, any news on this PR? Can I do something on my side?

[marksweb]

@corentinbettiol Yeah, you'll need to merge master into this branch and resolve the conflicts.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This will now be closed due to inactivity, but feel free to reopen it.

[codecov]

Codecov Report

Merging #1255 (cf2dcd6) into master (b5213c3) will increase coverage by 0.17%.
The diff coverage is 100.00%.

❗ Current head cf2dcd6 differs from pull request most recent head 986d71e. Consider uploading reports for the commit 986d71e to get more accurate results

@@            Coverage Diff             @@
##           master    #1255      +/-   ##
==========================================
+ Coverage   71.76%   71.94%   +0.17%     
==========================================
  Files          66       66              
  Lines        3124     3144      +20     
  Branches      451      453       +2     
==========================================
+ Hits         2242     2262      +20     
  Misses        729      729              
  Partials      153      153              

Impacted Files	Coverage Δ
filer/admin/folderadmin.py	71.86% <100.00%> (+0.04%)	⬆️
filer/admin/tools.py	79.48% <100.00%> (+2.67%)	⬆️
filer/templatetags/filer_admin_tags.py	88.31% <100.00%> (+1.74%)	⬆️

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[corentinbettiol]

I hope that it doesn't create too many conflicts with the pull request adding SVG icons and support in general.

@jrief I replaced the bits of code still using the old icons instead of svgs files, it looks great!