Fixed #24001 -- Added range fields for PostgreSQL.

Added support for PostgreSQL range types to contrib.postgres.

- 5 new model fields
- 4 new form fields
- New validators
- Uses psycopg2's range type implementation in python

tests/postgres_tests/migrations/0002_create_test_models.py

@@ -92,3 +92,26 @@ class Migration(migrations.Migration):
             bases=None,
         ),
     ]
+
+    pg_92_operations = [
+        migrations.CreateModel(
+            name='RangesModel',
+            fields=[
+                ('id', models.AutoField(verbose_name='ID', serialize=False, auto_created=True, primary_key=True)),
+                ('ints', django.contrib.postgres.fields.IntegerRangeField(null=True, blank=True)),
+                ('bigints', django.contrib.postgres.fields.BigIntegerRangeField(null=True, blank=True)),
+                ('floats', django.contrib.postgres.fields.FloatRangeField(null=True, blank=True)),
+                ('timestamps', django.contrib.postgres.fields.DateTimeRangeField(null=True, blank=True)),
+                ('dates', django.contrib.postgres.fields.DateRangeField(null=True, blank=True)),
+            ],
+            options={
+            },
+            bases=(models.Model,),
+        ),
+    ]
+
+    def apply(self, project_state, schema_editor, collect_sql=False):
+        PG_VERSION = schema_editor.connection.pg_version
+        if PG_VERSION >= 90200:
+            self.operations = self.operations + self.pg_92_operations
+        return super(Migration, self).apply(project_state, schema_editor, collect_sql)