Started working on user-defined-fields for all entities (references #176)

migrations/0066.sql

@@ -0,0 +1,31 @@
+CREATE TABLE userfields (
+	id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
+	entity TEXT NOT NULL,
+	name TEXT NOT NULL,
+	caption TEXT NOT NULL,
+	type TEXT NOT NULL,
+	show_as_column_in_tables TINYINT NOT NULL DEFAULT 0,
+	row_created_timestamp DATETIME DEFAULT (datetime('now', 'localtime')),
+
+	UNIQUE(entity, name)
+);
+
+CREATE TABLE userfield_values (
+	id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
+	field_id INTEGER NOT NULL,
+	object_id INTEGER NOT NULL,
+	value TEXT NOT NULL,
+	row_created_timestamp DATETIME DEFAULT (datetime('now', 'localtime')),
+
+	UNIQUE(field_id, object_id)
+);
+
+CREATE VIEW userfield_values_resolved
+AS
+SELECT
+	u.*,
+	uv.object_id,
+	uv.value
+FROM userfields u
+JOIN userfield_values uv
+	ON u.id = uv.field_id;