Revert "Merge pull request #5852 from margori/3393-activity-stream-keeping-retracted-participations"

This reverts commit 096fa2dd, reversing
changes made to f7d11051.

First iteration to update Help section

Changes from Fla

update Changelog

remove weird merge thing

think of the padding and margin

Added line to changelog for bug fix of issue #5631.

Processing the 'mouseleave' event only if we've left both the parent and the hovercard.

Fixed indentation.

Replaced issue id with pull request id and fixed indentation.

tests for reshares

Changelog.md update

fixing a style issue

removed unnecessary semicolon

Adapt cukes to work with new capitalisation rules

Fix merge conflict

Add warning about MySQL collation

Fix database index length

This allows new databases to be created with utf8mb4, on MySQL. The maximum
column size is 767 bytes. Each character is 4 bytes long -> 767 / 4 = 191
characters for the column.

Fixes also mobile bookmarklet services.