ADD DIRECTORY EMPTY + FR (updated) +EL indent+ fix JSON error (cs,fi,hu)

[fabriceci]

I add a entry DIRECTORY_EMPTY, to handle the case when you try to download a an empty directory (Zip).

I do on the way :

• correction of a JSON Error on the file ( cs, fi, hu)
• reindented the file el
• completed the French translation

Suggestions (I did not do that is the PR) :

• normalize files

  • uppercase or lowercase all keys
  • sometime there is %s and other time '%s'

    "DIRECTORY_ALREADY_EXISTS": "The directory '%s' already exists.",
    "DIRECTORY_NOT_EXIST": "The directory %s does not exist.",
  

• rename (I think) summary_size="Size" to summary_size="Used space"

• ask help on the homepage to complete translations

[fabriceci]

Have you some questions about this?

[psolom]

No it's ok, I'm going to merge it in few days. Right after the merging the previos PR.