Change some @param array phpdoc tags to be @param Object[], fill in DataTableMap::deleteRow and start documenting ArchiveProcessor.

Tweaking some docs, fixing build, fixing a MultiSites css issue and fixing regression in recent DataTable filter cleanup.

Refs #4200, remove  parameter from Truncate filter,and  document AddSummaryRow and Truncate filters.

Refs #4200, make DataTable:: private & add public methods necessary, tweaking some filter docs, and remove AddConstantMetadata filter.

added interface for dataTable to be able to define the expected type in a function, maybe it makes sense to add/remove some methods from the interface?

 * updating all variables/methods containing Referers
 * RENAMING custom segments definition, and custom scheduled reports definition, so that when they load "Referers" segment/report it still works as expected
 * RENAMING old archived data so that archived blobs are called Referrers
  * Reverting part of 0deb2bbb
  * Update integration tests generating PDF+HTML with images on my dev box (GD 2.1 and PHP 5.5)

Notes:
  - Fix bugs in DataTable class where getRowFromLabel would fail if summary row label is returned.
  - Fix regression caused by datatable visualization refactor (add_total_row property was effectively ignored).
  - Added x_axis_step_size property to jqplot graph.

Refs #4040, #4041, move AllColumns ViewDataTable & Goals ViewDataTable logic to HtmlTable visualization class & remove those classes. Revised the way visualizations default/override view properties. Cleaned up the ViewDataTable class a bit. Added base type for datatable visualizations.

renaming Unzip to Uncompress,
Renaming Tracker/Referer to Tracker/Referrer,
and few more

Refs #4040, converted UserCountry plugin to use display properties instead of ViewDataTable methods.

Refs #4059 Work in progress: Conversion to use Namespaces: Period*, Metrics, Segment, SegmentExpression, PluginsManager.
Removed some deprecated code.

Refs #4041, fix bug in displaying DBStats reports by redefining how columns_to_display view property defaults and allow unique visitors to be displayed on reports that have it, outside of period=day.

Removing feature: enable_archive_parents_of_datatable = 0 (main reason: there is no test, second reason: there is no public plugin using this feature AFAIK)
@Timo if you need this feature, let's put it back with some tests..
 Refs #2697

such as removing duplicate code and a lot of refactoring, the code is now much more readable!

Refactored archive data querying code. Removed tree-like data structure from Piwik_Archive, added memory optimizations for archiving (not storing archive processing instances), added optimization for querying data indexed by site + date, added ability to select multiple blobs/metrics at once (from different plugins), added optimization to Piwik_ArchiveProcessing_Period where numerics/records are selected all at once instead of one at a time.

Also added data access layer object for archive querying code, allowed anonymous function objects to be used as DataTable filters, and removed 'timestamp' DataTable metadata.