Move MR Builds tab next to Commits
Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/4132
@dzaporozhets We've got two people who feel strongly about this now, @sytses filed an issue for it :)

See merge request !2128
Link to correct (source) project on MR builds tab
Used to link to `gitlab-org/gitlab-ce/commits/<branch-name>`, now links to correct project.
See merge request !2115
Fix headers of milestone and snippet show pages
Fix layout, and move "Edit" button to very right just like issue/MR.
Before:


After:


cc @skyruler
cc @rspeicher 8.3 please!
See merge request !2104
Fix right margin of control list
Before:

After:

See merge request !2114
Issuable sidebar tweaks
- Move cross-project reference down
- ~~Fix "Notifications" label color~~ Reverted
- ~~Use regularly colored button for "Subscribe"/"Unsubscribe"~~ Reverted
Before:

After:
(Only the moved cross-project reference is still relevant, other changes have been reverted)

cc @skyruler
cc @rspeicher 8.3 please!
See merge request !2105
Fix double right border in MR discussion
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
# Before

# After

cc @skyruler
See merge request !2113
Make profile navigation full wide
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
## Before

## After

See merge request !2076
Move Markdown/reference logic from `Gitlab::Markdown` to `Banzai`
- Moves from `Gitlab::Markdown` to `Banzai`
- Moves filters and pipelines into their own namespace: `Banzai::Filter` and `Banzai::Pipeline`
- No more `autoload`!
- Split up `Gitlab::ReferenceExtractor` into `Banzai::ReferenceExtractor` and `Gitlab::ReferenceExtractor`
- Replace `something(load_lazy_references: true)` by `Gitlab::ReferenceExtractor.lazily { something }`
Goes from:
```ruby
def referenced_merge_requests
references = [self, *notes].flat_map do |note|
note.all_references(load_lazy_references: false).merge_requests
end.uniq!
Gitlab::Markdown::ReferenceFilter::LazyReference.load(references).uniq.sort_by(&:iid)
end
```
to
```ruby
def referenced_merge_requests
Gitlab::ReferenceExtractor.lazily do
[self, *notes].flat_map do |note|
note.all_references.merge_requests
end
end.sort_by(&:iid)
end
```
See merge request !2027