Allow two decimal places in cable length, show training item IDs in selectpicker

Will close #540

assets/migrations/0028_alter_asset_length.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.19 on 2023-05-24 22:03
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('assets', '0027_asset_nickname'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='asset',
+            name='length',
+            field=models.DecimalField(blank=True, decimal_places=2, help_text='m', max_digits=10, null=True),
+        ),
+    ]