Cross-reference code navigation powered by Sourcegraph

Sourcegraph make it easier to navigate code, is open source, and already has an integration with GitLab.

We should integrate Sourcegraph in to GitLab, so that installing GitLab includes Sourcegraph and you automatically get powerful code navigation out of the box.

Proposal

• support Sourcegraph.com without a browser extension in blob view, diffs, and Web IDE
• ship Sourcegraph with GitLab

Links / references

Twitter thread: https://twitter.com/sqs/status/1046986755919024129

Other open source alternatives:

• OpenGrok https://oracle.github.io/opengrok/ which supports C/C++
• Zoekt https://github.com/google/zoekt with a demo on https://cs.bazel.build/?q=%20 example on https://cs.bazel.build/search?q=+r%3Atorvalds+craz%5Byi%5D&num=50 and mention on https://news.ycombinator.com/item?id=16123467 – Sourcegraph uses this I think