1. We now display the index of the current issuable among all its project's
issuables, of the same type and with the same state.
2. Also, refactored a bit the Issuable helpers into a new IssuablesHelper
module.
3. Added acceptance specs for the sidebar counter.

- Apply the RelativeLinkFilter filter to other formats, e.g.,
  reStructuredText so links from the Files view or the Project view work
- Remove the AsciidocPipeline pipeline

Fixes #3533.

[WIP]

All inputs of type `search` will have the gray background
and search icon centered.
Because the search magnifier is a bg image,
I had to hide it with `[value=""]`.
I added a little javascript to make sure each input always has it's
own value.

Now it returns the fully-formatted message so we can be consistent about
how it's shown.

Somehow this test existed on EE but not in CE, so it started failing
after a bad CE-to-EE merge.

Closes #5908

* It is more performant given now we process all the diff file instead
  of processing line by line.
* Multiline comments are highlighted correctly.

Signed-off-by: NRubén Dávila <rdavila84@gmail.com>

Closes #4002

see bug #3758

If the User object is already known before calling this method being
able to re-use said object can save us an extra SQL query.

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

The controller_path includes namespaces, where controller_name only includes the class name without controller

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Replaced:
* "Accepted" with "Merged"
* "Rejected" with "Closed"
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

The purpose for this override is now handled by `ExternalLinkFilter`.

Minor refactoring, add specs, changes arguments to use keywords.

Consolidates the helpers related to user preferences.

Renames `app_theme` to `user_application_theme` to better explain what
it is.

Now we can simply loop through all themes, among other things.

This also removes the `dark_theme` / `light_theme` classes and the
`theme_type` helper, since they weren't used anywhere.