adding in backgrounds framework

schema/backgrounds.sql

@@ -0,0 +1,10 @@
+-- -*- mode:sql sql-product:sqlite -*-
+
+CREATE TABLE backgrounds (
+  bg_id INTEGER PRIMARY KEY,
+  bg_name TEXT NOT NULL UNIQUE,
+  bg_descr TEXT NOT NULL,
+  sources_id INTEGER NOT NULL,
+  sources_pages TEXT NOT NULL,
+  FOREIGN KEY (sources_id) REFERENCES sources(sources_id)
+);