This method can be used to find multiple projects for multiple paths.
For example, take this snippet:

    Project.where_paths_in(%w{gitlab-org/gitlab-ce gitlab-org/gitlab-ee})

This will return an ActiveRecord::Relation containing the GitLab CE and
GitLab EE projects.

This method takes care of matching rows both case-sensitively and
case-insensitively where needed.

Project.find_with_namespace in turn has been modified to use
Project.where_paths_in without nuking any scoping (instead it uses
reorder(nil)). This means that any default scopes (e.g. those used for
"pending_delete" stay intact).

The method Project.where_paths_in was added so the various Markdown
filters can use a single query to grab all the projects referenced in a
set of documents, something Project.find_with_namespace didn't allow.

Award emoji fixes

Fixes #18357 #18325 and #18424

See merge request !4550

yes -> true
no -> false
. frequent -> .frequent-emojis

[ci skip]

Properly quote table name in Rake task for MySQL and PostgreSQL compatibility

!4318 broke the gitlab:db:drop_tables functionality for PostgreSQL.
    
Closes #15259

See merge request !4577

Add milestone expire date to the right sidebar

## What does this MR do?
Shows milestone expire date tooltip in the sidebar. It also shows the tooltip when sidebar is collapsed.

## Are there points in the code the reviewer needs to double check?
`common_utils.js.coffee` and `milestones_helper.rb` should be reviewed deeply.

## What are the relevant issue numbers?
https://gitlab.com/gitlab-org/gitlab-ce/issues/17355

## Screencast
![zngAcytBWq](/uploads/bd8514506aa5010aef9b081455ee90af/zngAcytBWq.gif)

See merge request !4448

!4318 broke the gitlab:db:drop_tables functionality for PostgreSQL.

Closes #15259

Checks for undefined when inserting autocomplete into textarea

## What does this MR do?

Correctly checks for undefined before inserting anything into the textarea when using autocomplete. This happens because the loading indicator tries to insert `@undefined` which we dont want to insert.

See merge request !4561

Fix bug with SQL syntax error during backup restoration

## What does this MR do?
It properly escapes the table name in the `DROP TABLE IF EXISTS ...` statement used during restore of a backup.

## Are there points in the code the reviewer needs to double check?
Please check compatibility with PostgreSQL

## Why was this MR needed?
Fix an issue with backups can not be restored if MySQL is used as database for GitLab.

## What are the relevant issue numbers?
#15259 

## Screenshots (if relevant)
-

See merge request !4318