Json-Generator: Show all strings with pretty print

[ScreamingDev]

The Json-Generator filtered untranslated string out for the JSON-File.
With such file a developer needs more time to translate things
because he needs to look it up several times.

For a better workflow all translatable strings are included in the JSON-File.
With pretty-print (>= PHP 5.4) the JSON is more human readable.

[mlocati]

What happens on PHP 5.3 (JSON_PRETTY_PRINT is not defined)?

[ScreamingDev]

Wow. You like to keep that PHP 5.3 support?
PHP itself does not support that anymore.

I might be able to fix this.

[mlocati]

Yes, this library still supports 5.3 (as you can read from the composer.json file)

[ScreamingDev]

Thanks. I contributed to some projects and some like to drop old PHP.
For yours I've taken a workaround from http://php.net/manual/en/function.json-encode.php#80339

Feel free to merge or not :)

[oscarotero]

I think a better way is to allow to configure how the json can be generated, using a public static variable. For example:

Gettext\Generators\JsonDictionary::$options = JSON_PRETTY_PRINT;

[oscarotero]

I close this pull request because I've added the $options static property to JsonDictionary generator

[ScreamingDev]

Thank you! I didn't had time for that recently due to so much community driven events.
I'll add that to my project https://github.com/sourcerer-mike/wp-easy-translate after all the trouble ;)