Updated Dutch localization

[iMicknl]

No description provided.

[coveralls]

Coverage decreased (-1.4%) to 52.786% when pulling cdfc2f0 on iMicknl:update_dutch_locale into 4a1a9a5 on Microsoft:master.

[corinagum]

Thanks for the contribution! Please add your username to LOCALIZATION.md and resolve merge conflicts :)

[iMicknl]

@corinagum I will fix the merge conflicts. My username is already in the LOCALIZATION.md from the V3 version.

@compulim should these files Localisation files be excluded from coveralls?

[compulim]

@iMicknl I won't look too much into coveralls right now.

Design of tests:

• 90%+ should be visual regression test
  • To lower effort to test stuff
  • To lower effort to verify how a feature work
  • To prevent test bugs (e.g. prevent writing assertions that didn't look at full picture)
• Visual regression test is not great for small piece of isolated code, like localization
  • At a latter push of code coverage, we should add unit tests specifically for localization code, so it won't dip our code coverage a lot

[compulim]

@corinagum could you do a quick check against machine translator?
@iMicknl we check against machine translator just to prevent accidentally merging in profanity words 😉

[corinagum]

Machine translation looks good to me. :) @iMicknl could you answer one question above? Then this is ready to merge.