Render cross reference in issue title

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Add cross-project reference tooltip for merge request

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'show-cross-project-ref' into 'master'

Show cross project ref

Fixes #1661

See merge request !1292