Thanks to @edoceo

Refs #3089, show previous/next visitor links as arrows that appear only on hover of the upper left section in the visitor profile.

Using json we lost some overhead, and for PHP 5.3 there is no JSON_PRETTY_PRINT so we loose even more.

function_exists only works for create_function results, not closures.

This allows the IDE to pick up all code!

refs #4113

- it's now able to filter/clean translations, which shouldn't be done in tests only
- uses the new Translate\Filter and Translate\Validate classes
- is now able to write the files, and not only return data and path to write

no need to remove unrequired files, as they won't be in download package anymore (removed on otrance server)

moved translations for SecurityInfo plugin to its own language files, as it will be moved to its own repository

moved translations for VisitorGenerator plugin to its own language files, as it will be moved to its own repository