[Debug] Add link to the output of debug function

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

![link](https://cloud.githubusercontent.com/assets/408368/4403994/98f89526-44ab-11e4-8fa8-85b58afb738a.png)
![lin2](https://cloud.githubusercontent.com/assets/408368/4403998/abbabee6-44ab-11e4-9117-f786718dfb37.png)

you need to handle the case of ``|file_link`` returning ``false`` when the link format is not configured (for people using an IDE or an OS not supporting it, or just ignoring that the feature exists)