Separate reference gathering from rendering
This is a required step to allow batch processing when gathering references. This in turn would allow grabbing (for example) all mentioned users of an issue/merge request using a single query.
cc @rspeicher @DouweM
See merge request !3969
Loads move issue dropdown async
To keep the style of the dropdown the same as the other dropdowns in the issue form, it uses select2 rather than our new dropdowns.

Closes#16563
See merge request !4160
Issuable filtering improvements
This improves the filtering of issues and merge requests by creating a single file that encapsulates all the filtering. Previously this was done with a file for issues and a file for merge requests.
Created the ability for the text search to be done alongside other filterables. Previously because this was outside the filterable form, this wasn't possible and would instead do either filter dropdown or text filter - not both. Fixes#4252
Fixed issue with not being able to filter and sort issues without refreshing the page. Fixes#15269
See merge request !3699
Issuable form due date
For some reason, this was never in the original merge request for due date?

Closes#15516
See merge request !3895
Wrap "No groups found" message with a .nothing-here-block
The "No groups found" message's style is inconsistent with the other empty messages.
## Screenshots
### Empty groups

### Empty projects

See merge request !4137
This improves the filtering of issues and merge requests by creating a single file that encapsulates all the filtering. Previously this was done with a file for issues and a file for merge requests.
Created the ability for the text search to be done alongside other filterables. Previously because this was outside the filterable form, this wasn't possible and would instead do either filter dropdown or text filter - not both.
Add new shortcuts
Closes#14904
- On a project: `i` To navigate to New Issue page.
- On a issuable: `l` To open Label dropdown on a issuable.
- Global: Typing `?` multiple times now toggles the modal.
See merge request !3686
Allow filtering by Owned projects on dashboard page
Closes#3799

See merge request !3762
Ci::Commit becomes a Pipeline object
1. Ci::Commit receives context: ref, :tag.
1. One Ci::Commit describes a one Pipeline
1. Pipeline is created from `.gitlab-ci.yml`
1. Pipeline is a ordered group of builds
1. We test MR against Pipeline
1. Pipelines have a separate view (https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/3703)
1. Pipeline can be triggered from UI (https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/3703)
1. Later we change `Trigger -> TriggerRequest -> Build` to `Trigger -> Pipeline` (future)
1. We add a Pipeline Hook that will be triggered on Pipeline status change (future)
1. We extend notifications to use `Pipeline Hook` to send summary on pipeline changes (future)
After merging that I'll prepare a separate MR that will unify naming, database columns, table names:
```
Ci::Commit -> Pipeline
Ci::Build -> Build
CommitStatus -> Job
GenericCommitStatus -> ExternalJob
ci_commits -> pipelines
ci_builds -> jobs
```
This MR implements first 5 points.
This is made to solve this issue https://gitlab.com/gitlab-org/gitlab-ce/issues/14149.
See merge request !3653