Do not capitalize paasdag/pinksterdag/kerstdag

[c960657]

According to official Dutch ortography (Green Booklet = Groene Boekje), public holidays such as eerste/tweede paasdag/pinksterdag/kerstdag should not be written in title case.

The alternative spelling, White Booklet (Witte Boekje), recommends title-case, i.e. Eerste/Tweede Paasdag/Pinksterdag/Kerstdag.

According to Wikipedia (https://en.wikipedia.org/wiki/White_Booklet), Groene Boekje has some traction in the Netherlands but not in Belgium, so the Green Booklet spelling should be used for nl_BE.

I don't know how widespread Green Booklet is in the Netherlands, but it is my impression that the official Green Booklet is a more neutral choice for nl_NL for a general-purpose library like Yasumi. However, my knowledge of Dutch is very limited, so please correct me if I'm wrong (I'm looking at you, @stelgenhof :-).

References:
https://onzetaal.nl/taaladvies/feestdagen/
https://www.languagepartners.nl/blog/nederlands-nt1/valentijnsdag-of-valentijnsdag/
https://www.vandale.nl/gratis-woordenboek/nederlands/betekenis/kerstdag#.XEtn1s9KhfI

[stelgenhof]

@c960657 Thanks for the PR!

Although I haven't lived in the Netherlands for a while, I recall this has been quite a debate back in 2005. Some (media) companies boycotted the Green booklet as they disagreed with some of the rules.

Just read, that in Belgium, the have introduced a Yellow Booklet, since there are many de facto words (casual words) so common, they wanted to make it more official.

Not sure yet what would be the best way forward.

Cheers! Sacha

[stelgenhof]

@c960657 I took the time to read a bit more about the rules regarding title case for the Dutch holidays. Indeed compound words with the name of the holiday are written in lowercase. Reference to the event itself (e.g. Christmas), is written with a capital letter.