Improve Dutch translation

[wbolster]

This PR contains an updated Dutch translation. This fixes a bunch of plain wrong translations, making the app hard to understand, and also corrects various grammatical and spelling mistakes.

[wbolster]

Note to reviewer: I've reformatted the (previously misaligned) XML. Using git show --word-diff (or another git command that understands --word-diff) results in a readable diff, e.g.:

diff --git a/Dimmer/res/values-nl/strings.xml b/Dimmer/res/values-nl/strings.xml
index 1c5edc2..61891e4 100644
--- a/Dimmer/res/values-nl/strings.xml
+++ b/Dimmer/res/values-nl/strings.xml
@@ -1,39 +1,36 @@
<?xml version="1.0" encoding="utf-8"?>
<resources>
  <string name="app_name">Dimmer</string>
  <string name="action_settings">Instellingen</string>
  <string [-name="guide">Veeg-]{+name="guide">Klik+} omhoog en omlaag om de helderheid [-in-]{+aan+} te [-stellen.</string>-]{+passen.</string>+}
  <string [-name="pref_auto_title">Automatiche Modus</string>-]{+name="pref_auto_title">Automatische modus</string>+}
  <string name="pref_auto_summary">Automatisch aanpassen aan de omgeving.</string>
  <string name="pref_auto_lux_state">Huidig omgevingslicht:</string>
[...]

(and so on)

[wbolster]

just wondering... is this project still alive?