Fixed issue with sidebar edit links toggling anchor
This caused an issue with the page scrolling from the bottom to the top. Also stopped the dropdown links doing the same.
See merge request !3819
Removed commented text from system notes

See merge request !3836
Fixed issue with new MR form layout
Currently it is all over the place:

Now:

See merge request !3837
Fixes issue with note form inheriting text color
It was only really noticeable on dark themed diffs

See merge request !3834
add slack notifications for wiki pages
## What does this MR do?
Lets the Slack service be configured to send notifications when wiki pages are created or edited.
## Are there points in the code the reviewer needs to double check?
I'm just starting to get familiar with the Gitlab codebase and I was unsure on how to get the wiki page url to pass it to the slack message, on whether or not I needed to refactor the create/update methods for wiki pages from the controller to a service (but seemed necessary to test it better), and if I needed to add a column to the web hooks table or if the services table would have been enough. Please let me know if I should change anything and I will improve the MR, thanks for checking :)
## Why was this MR needed?
Related to #563 and fixes#4233.
See merge request !2998
Add raw build trace output
Closes#15308, #15147
Changes in the UI:
- on finished build:

- on running build:

See merge request !3767
Sanitize branch names for confidential issues
- When creating new branches for confidential issues, prefer a branch name like `issue-15` to `some-sensitive-issue-title-15`.
- The behaviour for non-confidential issues stays the same.
Closes#14566
See merge request !3671
Configuring of points per UDP packet
Related to https://gitlab.com/gitlab-com/operations/issues/195. This option would allow us to experiment with finding a good balance between points-per-packet and the UDP packet size.
cc @pcarranza
See merge request !3816
Remove persistent XSS vulnerability in `commit_person_link` helper
Because we were incorrectly supplying the tooltip title as
`data-original-title` (which Bootstrap's Tooltip JS automatically
applies based on the `title` attribute; we should never be setting it
directly), the value was being passed through as-is.
Instead, we should be supplying the normal `title` attribute and letting
Rails escape the value, which also negates the need for us to call
`sanitize` on it.
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15126
See merge request !1948
Trigger filtering after ajax is complete in dropdown

Closes#15186
See merge request !3813
This allows users to configure the number of points stored in a single
UDP packet. This in turn can be used to reduce the number of UDP packets
being sent at the cost of these packets being somewhat larger.
The default setting is 1 point per packet so nothing changes for
existing users.
Check permissions when sharing project with group
## Summary
Unprivileged user was able to share project with group he didn't have access to, and therefore gain partial access to that group, which opened possibilities for further actions like listing private projects in that group.
See https://gitlab.com/gitlab-org/gitlab-ce/issues/15330
## Fix
This change introduces additional check for group read access.
## Further work
We can think about preventing such problems in the future (this is quite common problem) by moving permissions checks to another layer of abstraction (TBD).
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/15330
See merge request !1949