Provide blackfire like user interface for debugging requests and queries

[mrow4a]

Currently, diagnostic log is pretty simple and fully prepared for user interface in the form as here https://github.com/owncloud/diagnostics#usage

Would be "timeline" like user interface be interesting here? So that click on the request will create a timeline of events and queries, with debug trace (who called it where) etc?

Sth like clockwork, but for any type of request issued on the server, and a bit simpler.

@butonic @PVince81 @DeepDiver1975