Better logging messages in core:archive output

 * made output more consistent and easier to read by a human
 * better summary report for "Skipped websites" stats

Fixes #8216, fixed typo that caused ' beeing replace with ) in segment editor

Fixes #6593, in segment SQL join log_conversion on idvisit so segmentation on Actions (page url, page title...) works for goals and ecommerce reports

Allow plugins to add query parameters to optout form

Catch exceptions in ScheduledReports generation so reports will still generate if individual reports fail

When detecting campaign info in Referrers check _rcn and _rck query parameters.

Correctly parse all URL schemes in UrlHelper::isLookLikeUrl().

Default visit custom variables array in GoalManager class.

Adding System test case that showcases the bug: ecommerce report with segment "Page URL" shows 0 data

Add test for ScheduledReports API.generateReport exception catching. Includes making Proxy constructor public (for mocking) and using Common::sendHeader in ReportRenderer (so headers won't be sent twice).

Catch exceptions when getting individual reports during scheduled reports generation so reports will still be sent even if individual reports fail in some way.