Fix some misc. things :)

[ddabble]

Proposed changes

Improvements

• Replaced the deprecated execCommand() for copying to the clipboard, with using the Clipboard API (2a41c00e854df84d4486a90aba85ba7a0f6a7120)
• Added and improved some comments in settings.py (c0f7856e2f83bc0fb95f93d199ebaa91e86857e2)

Fixes

• Fixed AttributeError when the request object is None for some requests (2eec7e0d09df900011833dd808a9834db93bf613)
• Fixed the "View site" button in the English Django admin not leading to the English front page (35f9eea89c34e54ba356e8f5c12f355612f722ba)

Other changes

• Code cleanup (082d487a37940176e6327c499b798688d6ad4cf7)
• Only enable the debug toolbar if the DEBUG setting is True (5af19e93d4e066c009aebea69fc831923e87ff57)

Areas to review closely

None in particular.

Checklist

(If any of the points are not relevant, mark them as checked)

• [x] Created tests that fail without the changes, if relevant/possible
• [x] Made sure that your code conforms to the code style guides and that any common code smells have been addressed
  • (It's not intended that you read through this whole document, but that you get yourself an overview over its contents, and that you keep it in mind while taking a second look at your code before opening a pull request)
• [x] Added sufficient documentation - e.g. as docstrings or in the README, if suitable
• [x] Added your changes to the "Unreleased" section of the changelog - mainly the changes that are of particular interest to users and/or developers, if any
• [x] Added a "Deployment notes" section above, if anything out of the ordinary should be done when deploying these changes to the server

[ddabble]

Merging without explicit approval from another member, as the Dev committee agreed to merge these changes and assume they're relatively bug-free, simply to get things done quicker.