Tracking API: new function setPageCharset to set the character set used on the tracked page #3565

By default Piwik expects UTF-8 encoded strings. Some Tracking API clients or websites are built in non utf8 eg. iso-8859-1

When non utf8 strings are set as "page title" or if Page URL parameters values are encoded in non utf8, we should decode these and reencode in UTF8.

In Javascript API the charset is automatically detected from the document charset.

In PHP This ticket will add a new API method to set the charset of strings recorded and tracked in piwik.

(In [7521]) Site search improvements

• Support &kwd[]= notation fixes #3454
• Support random text case fixes #3539
• Fixes umlauts regression with non utf8 encoding: Fixes #3450
• Adding setPageCharset() method to Tracking API FIxes #3565