fix link on docs-develop.pleroma.social

See merge request pleroma/pleroma!1876

[#1304] User.Info deprecation

Closes #1304

See merge request pleroma/pleroma!1851

# Conflicts:
#	lib/pleroma/notification.ex

activitypub: visibility: refactor is_public?() to use JSON-LD safe accessors

Closes #1326

See merge request pleroma/pleroma!1874

tests: transmogrifier: add explicit regression tests for JSON-LD strings as single-element array fuckery

See merge request pleroma/pleroma!1873

tests: transmogrifier: add explicit regression tests for JSON-LD string to single-element array deserialization

There appears to be confusion on whether or not Pleroma can handle this particular
sin of JSON-LD.  It can, and we will add regression tests to prove that it can handle
this particular sin.  Which, by the way, this is actually not a "feature" of JSON-LD,
but whatever.

Direct messages should provide a distinct push notification subject

See merge request pleroma/pleroma!1864

Do not include notifications from blocked users when with_muted is set

See merge request pleroma/pleroma!1869

This is not what with_muted is for per documentation and it was agreed
on irc that this behavior doesn't make sense.

[#1275] Markers /api/v1/markers

See merge request pleroma/pleroma!1852

# Conflicts:
#	lib/pleroma/user/info.ex
#	lib/pleroma/web/activity_pub/activity_pub.ex
#	lib/pleroma/web/activity_pub/transmogrifier.ex

activitypub semantics

See merge request pleroma/pleroma!1798

[#1304]. Post-merge fixes. Merge branch 'develop' of git.pleroma.social:pleroma/pleroma into 1304-user-info-deprecation

# Conflicts:
#	CHANGELOG.md
#	lib/pleroma/notification.ex
#	lib/pleroma/user.ex
#	lib/pleroma/user/info.ex
#	lib/pleroma/web/admin_api/admin_api_controller.ex
#	lib/pleroma/web/ostatus/handlers/follow_handler.ex
#	lib/pleroma/web/ostatus/ostatus.ex
#	lib/pleroma/web/salmon/salmon.ex
#	lib/pleroma/web/websub/websub.ex
#	test/web/admin_api/admin_api_controller_test.exs
#	test/web/federator_test.exs
#	test/web/mastodon_api/controllers/conversation_controller_test.exs
#	test/web/ostatus/ostatus_controller_test.exs
#	test/web/ostatus/ostatus_test.exs
#	test/web/salmon/salmon_test.exs
#	test/web/websub/websub_test.exs

# Conflicts:
#	CHANGELOG.md
#	lib/pleroma/notification.ex
#	lib/pleroma/user.ex
#	lib/pleroma/user/info.ex
#	lib/pleroma/web/activity_pub/activity_pub.ex
#	lib/pleroma/web/admin_api/admin_api_controller.ex
#	lib/pleroma/web/ostatus/handlers/follow_handler.ex
#	lib/pleroma/web/ostatus/ostatus.ex
#	lib/pleroma/web/salmon/salmon.ex
#	lib/pleroma/web/websub/websub.ex
#	test/web/admin_api/admin_api_controller_test.exs
#	test/web/federator_test.exs
#	test/web/mastodon_api/controllers/conversation_controller_test.exs
#	test/web/ostatus/ostatus_controller_test.exs
#	test/web/ostatus/ostatus_test.exs
#	test/web/salmon/salmon_test.exs
#	test/web/websub/websub_test.exs

add missing migration to drop websub table

See merge request pleroma/pleroma!1868

Misc. fixes / improvements.