Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- .github/ISSUE_TEMPLATE/bug_report.md
  Took our version.
- CONTRIBUTING.md
  Updated the embedded copy of upstream's version.
- README.md
  Took our version.
- app/policies/status_policy.rb
  Not a real conflict, took code from both.
- app/views/layouts/embedded.html.haml
  Added upstream's changes (dns-prefetch) and fixed
  `%body.embed`
- app/views/settings/preferences/show.html.haml
  Reverted some of upstream changes, as we have a
  page dedicated for flavours and skins.
- config/initializers/content_security_policy.rb
  Kept our version of the CSP.
- config/initializers/doorkeeper.rb
  Not a real conflict, took code from both.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -1,11 +1,17 @@
 ---
 name: Feature Request
-about: Suggest an idea for this project
+about: I have a suggestion
 
 ---
 
-[Issue text goes here].
+<!-- Please use a concise and distinct title for the issue -->
 
-* * * *
+<!-- Consider: Could it be implemented as a 3rd party app using the REST API instead? -->
 
-- [ ] I searched or browsed the repo’s other issues to ensure this is not a duplicate.
+### Pitch
+
+<!-- Describe your idea for a feature. Make sure it has not already been suggested/implemented/turned down before -->
+
+### Motivation
+
+<!-- Why do you think this feature is needed? Who would benefit from it? -->

.github/ISSUE_TEMPLATE/support.md

@@ -0,0 +1,10 @@
+---
+name: Support
+about: Ask for help with your deployment
+
+---
+
+We primarily use GitHub as a bug and feature tracker. For usage questions, troubleshooting of deployments and other individual technical assistance, please use one of the resources below:
+
+- https://discourse.joinmastodon.org
+- #mastodon on irc.freenode.net