Add missing Dutch translation strings

I merged en.json and nl.json via

  jq -s '.[0] * .[1]' en.json nl.json > nl2.json && mv nl2.json nl.json

Which adds all missing elements in nl.json that are present in
en.json. Take care,j I believe that it keeps the sorting from
en.json (alphabetical), so it might create a bigger diff than
necessary.

res/translations/nl.json

@@ -16,8 +16,13 @@
     "albums": "albums",
     "All": "Alle",
     "All Tracks": "Alle nummers",
+    "Allow multiple app instances": "Meerdere app-instanties toestaan",
     "Alt. URL": "Alt. URL",
+    "An error occurred": "Er ging iets fout",
     "An error occurred adding tracks to the playlist": "Er ging iets fout bij het toevoegen van nummers aan de afspeellijst",
+    "An error occurred updating the playlist": "Er ging iets fout bij het updaten van de afspeellijst",
+    "Appearance": "Uiterlijk",
+    "Application font": "Lettertype",
     "Are you sure you want to delete the server": "Ben je zeker dat je de server wil verwijderen",
     "Artist": "Artiest",
     "Artist (A-Z)": "Artiest (A-Z)",
@@ -28,6 +33,7 @@
     "Audiobook": "Audioboek",
     "Authentication failed": "Authenticatie mislukt",
     "Auto": "Auto",
+    "Automatically check for updates": "Automatisch controleren op updates",
     "Autoplay": "Automatisch afspelen",
     "Autoselect device": "Automatisch apparaat selecteren",
     "Back": "Terug",
@@ -35,6 +41,7 @@
     "BPM": "BPM",
     "Broadcast": "Broadcast",
     "Cancel": "Annuleren",
+    "Cast to device": "Cast naar apparaat",
     "Check for Updates": "Controleer op updates",
     "Close": "Sluiten",
     "Close to system tray": "Sluiten naar systeemvak",
@@ -56,6 +63,7 @@
     "Demo": "Demo",
     "_Description": "Beschrijving",
     "Disable server transcoding": "Schakel server transcodering uit",
+    "Disable automatic DPI adjustment": "Automatische DPI-aanpassing uitschakelen",
     "Disc number": "Schijf nummer",
     "Discography": "Discografie",
     "discs": "schijven",
@@ -66,6 +74,7 @@
     "Edit": "Bewerken",
     "Edit Playlist": "Bewerk afspeellijst",
     "Edit server": "Bewerk server",
+    "Enable LrcLib lyrics fetcher": "LrcLib lyricsdownloader inschakelen",
     "Enable system tray": "Schakel systeemvak in",
     "Enabled": "Ingeschakeld",
     "Enter": "Enter",
@@ -144,6 +153,8 @@
     "Previous": "Vorige",
     "Private playlist by": "Private afspeellijst door",
     "Public playlist by": "Publieke afspeellijst door",
+    "Random": "Willekeurig",
+    "Rating": "Beoordeling",
     "reissued": "heruitgave",
     "Recently Added": "Recent toegevoegd",
     "Recently Played": "Recent afgespeeld",
@@ -158,6 +169,7 @@
     "Save play queue on exit": "Bewaar wachtrij bij afsluiten",
     "Saved at": "Opgeslaan op",
     "Scrobble when": "Scrobble als",
+    "Search": "Zoeken",
     "Search Everywhere": "Overal zoeken",
     "Search page": "Zoekpagina",
     "Search playlists or new playlist name": "Zoek afspeellijsten of nieuwe afspeellijst naam",
@@ -183,6 +195,7 @@
     "Single": "Single",
     "Size": "Grootte",
     "Skip duplicate tracks": "Dubbele nummers overslaan",
+    "Skip SSL certificate verification": "SSL-certificaat verificatie overslaan",
     "Skip this version": "Deze versie overslaan",
     "Sort": "Sorteren",
     "Soundtrack": "Soundtrack",
@@ -193,7 +206,9 @@
     "Support the project": "Ondersteun het project",
     "Switch Servers": "Servers wisselen",
     "Testing connection": "Verbinding aan het testen",
+    "The request timed out": "Het verzoek is verlopen",
     "Theme": "Thema",
+    "This computer": "Deze computer",
     "Time": "Tijd",
     "Title": "Titel",
     "Title (A-Z)": "Titel (A-Z)",
@@ -225,7 +240,6 @@
     "You are running the latest version of": "Je hebt de laatste nieuwe versie van",
     "Quit": "Beëindigen",
     "Rescan Library": "Bibliotheek opnieuw scannen",
-    "Search": "Zoeken",
     "Owner": "Eigenaar",
     "To server": "Naar server",
     "Fav.": "Fav.",