Added marshmallow schemas

where/validation.py

+from marshmallow_sqlalchemy import SQLAlchemyAutoSchema
+from .model import Point, Category, Field
+
+class PointSchema(SQLAlchemyAutoSchema):
+    class Meta:
+        model = Point
+        include_relationships = True
+        load_instance = True
+
+
+class CategorySchema(SQLAlchemyAutoSchema):
+    class Meta:
+        model = Category
+        include_relationships = True
+        load_instance = True
+
+
+class FieldSchema(SQLAlchemyAutoSchema):
+    class Meta:
+        model = Field
+        include_relationships = True
+        load_instance = True
+        
\ No newline at end of file