Track feature feedback

Users can rate certain features / reports / pages by hovering a headline and sending us a thumbs up or down. It would be kinda nice if we could track this somehow with Piwik, eg as events.

We'd have to be careful since headlines could contain custom data, eg the report name but we do track the name of a report already anyway under circumstances and we do notify users about that. Sometimes feature names are translated so we maybe do not get aggregated stats for all features but for most. Note: The displayed headline is != feature name. The feature name is stored in an attribute of the headline element and usually translated into english and hard coded for some features to not have different feature names for the same feature that would usually depend on user data.

We would so far only get stats for feedback that was sent by users having this plugin enabled, maybe it would be ok to also track it in general for all instances? Not sure! We can as well just close this issue and not implement it if we cannot track it from all instances as it would not be really valuable.

No files, tests, or entry points are named. First locate the feature-feedback handling and existing Piwik event tracking, then determine whether feedback can be tracked across supported instances while preserving the stated headline and feature-name constraints; done means the scope and feasibility are resolved or the issue is closed.