refs #5863 another try to move translations into plugins. This time we always load all translations of all plugins that are not 3rd party and bogus. As the translation file will be cached the time to load the translation drops from > 10ms to 1ms
refs #5863 only load translations of core plugins and of plugins that are loaded
refs #5863 fixed some of the tests
refs #5863 fix more tests including installation UI tests
remove minimum requirement of 250 translations for core
update language files, that were not updated correctly due to previous removed requirement
fixed tests
refs #5863 we need to load core translations upfront as metadataLoader will try to load plugin translation directly after loading the plugin when the plugin translations are not loaded yet. Maybe better fix would be to defer loading the plugin getInformation until needed. Could also bring performance improvement
refs #5863 we need to pass the langCode to loadPluginTranslations() otherwise langCode will be always an empty string. If there is no plugin loaded yet and no language generate a simple cache file for core translations, load a translation only if a langCode is there
fix installation tests again since loadPluginTranslation wants to acess the config and it did not exist at this time
Merge pull request #6059 from piwik/5863_languageFilesInPlugin

fixes #5863 Move translations from core to plugins and cache all plugin translations for better performance