Make dark theme a user level property, lazy load dark CSS

- Also now respects the colour-scheme media query
- Added meta tag to tell the browser we support dark theme, allowing dark UA stylesheet if the user sends said media query
- Means you only have to set it once per account rather than once per machine
- Dark themed embeds!

RIGS/migrations/0040_profile_dark_theme.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.1.5 on 2021-02-06 10:43
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('RIGS', '0039_auto_20210123_1910'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='profile',
+            name='dark_theme',
+            field=models.BooleanField(default=False),
+        ),
+    ]

RIGS/models.py

@@ -26,6 +26,7 @@ class Profile(AbstractUser):
     is_approved = models.BooleanField(default=False)
     last_emailed = models.DateTimeField(blank=True,
                                         null=True)  # Currently only populated by the admin approval email. TODO: Populate it each time we send any email, might need that...
+    dark_theme = models.BooleanField(default=False)
 
     @classmethod
     def make_api_key(cls):

RIGS/templates/event_form.html

@@ -79,7 +79,7 @@
 
 {% block content %}
 {% include 'item_modal.html' %}
-<form class=" itemised_form" role="form" method="POST">
+<form class="itemised_form" role="form" method="POST">
     {% csrf_token %}
     <div class="row">
         <div class="col-12">