Correcting the NL date locale

Closes #212

See merge request !166

PHPMailer update

Closes #217

See merge request !169

All those updates affect only the dev environment.

Some fixes on comments

Fix #205 

See merge request !161

Task - merge dutch language from master

I also normalized the indentation from the current javascript "norm" of the project.

All `locale/` files of the b2d87230 commit are just from the change of indentation: Gitlab doesn't seem to have a "ignore whitespace" functionality yet, so that's better to be said...

See merge request !160

Update oc.json

Translated the remaining French bits

See merge request !159

Update br.json

translate missing strings
(made online with gitlab, sorry for the ugly branch name)

See merge request !158

Update composer.lock



See merge request !157

Disable when results are hidden

Fix #196

See merge request !154

Added missing translation for "Optional parameters"



See merge request !156

Update French Translation



See merge request !151

Update add_comment.php: update sendUpdateNotification parameters order



See merge request !150

Collapse by default optional parameters

To be cherry-picked on `release`.

See merge request !147

Allow to remove date in the poll creation wizard

CF MR !140 

To be cherry-picked in `release`.

See merge request !146

Added the missing title attribute

Fix #189

See merge request !145