Add unit tests for new Metrics Formatter classes and remove existing ones. Small change to Overlay included and bug fixes to metrics formatting code included.

Declares a process as finished as soon as a PID file is > 500bytes
(contains only PID) and output file is > 100MB (which should usually
not be larger than 100KB or 1MB) to prevent files growing up to many
GBs. I added unit and integration tests for the file size detection. It is
now possible to mock the methods file_exists and filesize although very
simple so far. Later we can allow to define callbacks or to define different
return values for different files or we can use something like vfsStream

refs #6417 this should fix some tests. Start initial value by 0 so first generated id will be 1

fix omnifixture creation was broken

refs #6417 wondering if omnifixture creation worked

refs #6417 acquire a lock per archive id which should be better

refs #6417 we have to generate the SQL in the update itself otherwise the update would fail at some point in the future if the tables signature changes

refs #6417 split updates into a separate update file otherwise it would not be executed for devs using Piwik from git

refs #6417 added some documentation

refs #6417 Piwik 2.9.0-b2 was released meaning we have to move it to b3

refs #6417 Piwik 2.9.0-b3 was released meaning we have to move it to b4

Fixes #6068, correctly decode JSON encoded ec_items query parameter values so escaped HTML is properly handled by tracker. Includes tests and a separate fix to tests:run command (command fails when --options is used w/ a group argument).

Extracted `Piwik::getJavascriptCode()` into a separate, non static class: `Piwik\Tracker\TrackerCodeGenerator`

`Piwik::getJavascriptCode()` is now deprecated in favor of the new class.

refs #5940 moved files into a subfolder framework, added autoloader to remove duplicated code to load autoload.php and to be able to register more autoloaders (eg for test files) on demand. This I got read of many includes that had to be updated all the time and that had to be updated all the time when moving iles

#6085 Removed $GLOBALS['PIWIK_TRACKER_DEBUG_FORCE_SCHEDULED_TASKS'] and replaced it with DEBUG_FORCE_SCHEDULED_TASKS