rewrite: Restructure to include GUI.

src/data/__init__.py

@@ -0,0 +1,9 @@
+from .conditions import Condition, condition, NULL
+from .database import Database
+from .models import RowModel, RowTable, WeakCache
+from .table import Table
+from .base import Expression, RawExpr
+from .columns import ColumnExpr, Column, Integer, String
+from .registry import Registry, AttachableClass, Attachable
+from .adapted import RegisterEnum
+from .queries import ORDER, NULLS, JOINTYPE