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

Correcting comment typo in file header

Fix #190 

See merge request !144

Rework on 1st page of poll creation



See merge request !142

Disabled autocompletion on the datepicker input

Avoid autocompletion of the datepicker input field to occur
(Step to reproduce : Long click on a datepicker input field)

See merge request !141

Update, fix and add breton translation to correct branch



See merge request !143