parse_vbox_lang.php produce quite a few errors and only work on a
single file. This should make it easier to update translations with
changes in VirtualBox. Introduced in reworked script:

  - single file or directory input (batch processing)

  - checks to make sure all strings are included in resulting dat file

  - checks to get an overview of phpVirtualBox files compared to
    VirtualBox files and if settingsGlobalLanguage.html is updated