#1214 ACP language editor improved

* finds possible translation problems, missing files and extra files ect
and show hints on list of files in editwith mode
* finds possible translation problems and show hints while editing in
editwith mode
* create files and folders on demand
* allow deletion of obsolete extra phrases from old language packs (this
option is not available when editing original mybb language pack)
* increased stability
* allows use of copy paste to aid translation
* fixes bug where part of variables to which we compare are not
displayed if not exists in edited file while in editwith mode

#1214