Keep BC w/ old Formatter class since it is likely used by 3rd party plugins. Move Numeric formatter to CoreVisualizations and do not mark w/ @api.

Fixes #7247, move default Formatter class to new Numeric metrics formatter and use in Graph visualization since jqplot requires numeric values in JSON data.

Making algorithm processing unique visitors across websites actually work, refs https://github.com/PiwikPRO/plugin-MetaSites/issues/3

Make MetricsFormatter a class with instance methods and move Html related functionality to derived class. Use FOrmatter in Metric::format calls so Metrics do not have to be aware of context of formatting, and so Metric::format methods will have less code redundancy.

Moved processed metrics computation to DataTableGenericFilter, removed new filters & implemented as methods in Report to avoid confusion regarding re-use, allow adding processed metrics as DataTable metadata and use this to rewrite AddProcessedMetrics filter, correct name of Metrics::getMappingFromIdToName function, added placeholder AggregatedMetric class for future, revise Metric/ProcessedMetric hierarchy (add methods for translation/etc.), allow .get API methods to use metadata to automatically figure out which columns to select, get EcommerceOrderWithItemsTest to pass.

coding style fixes, some PHPStorm inspection fixes, improved readability of code, few refactorings, all as part of our code cleanup strategy

Adding new PivotByDimension DataTable filter that can pivot a report by (almost) any dimension. The filter can pivot reports by their subtable dimension and can also pivot by other dimensions (by using segments).

Notes:

- in the UI, only pivoting by subtable is supported
- change to CSV DataTable renderer so column names w/ commas & quotes can appear in text
- change to XML DataTable renderer so column names w/ invalid XML characters can be rendered (bit of an iffy change, XML format needs an overhaul I think)
- includes new config option 'pivot_by_filter_enable_fetch_by_segment'
- includes additions to component metadata classes (ie, Report/Dimension)

refs #6162 when aggregating periods, do not sum 'Unique Users' metric as this is not a valid operation.

Refs #6109 New core metric: nb_users as the count of distinct user ids. Means "Active Users". Displayed in Visitors Overview, in metrics picker, in API response, in Metadata

refs #4996 interactions should be tracked now. As only the name is really mandatory created a new column content_name for now (instead of existing idaction_name, will maybe remove it again). Otherwise it is hard to know whether it was a content action or not and the actual problem was that maybe other actions already define an idaction_name which might be different to content_name. We need the content_name along other actions to match an interaction with an impression. Next: The client side and the redirect...

refs #4996 archiving of impressions should work now, displaying impressions should work (contentName => contentPiece and contentPiece => contentName). Next step: Matching interactions with impressions then this part is nearly done hopefully

added new staticCache to remove a lot of duplicated code and to have a nice interface, by caching the default metrics we reduce the calls to translate from 50k to 2k resulting in good performance improvement...

Piwik is a free/libre analytics platform. Refs #4455 GNU Package requirement to use free/libre instead of open source

refs #4609

refs #1816 by generating total values before the generic filters, we only have to request the first level dataTable in case it is a subtable

refs #1816 do not create metrics for ratio, instead add total values to tableMetadata and generate ratio in view

refs #1816 made it a bit more generic, request first level table only if needed, handle ecommerce columns