Revisited the persistence layer.

Simplified schema to focus on user and node.
Now possible to have sqlite via ODBC and/or mysql support, and select using configuration file.
Updated demo example.

library/persistence/implementation/sqlite/scripts/schema.sql

@@ -0,0 +1,36 @@
+PRAGMA foreign_keys = OFF;
+
+BEGIN;
+CREATE TABLE "users"(
+  "uid" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL CHECK("uid">=0),
+  "name" VARCHAR(100) NOT NULL,
+  "password" VARCHAR(100) NOT NULL,
+  "salt" VARCHAR(100) NOT NULL,
+  "email" VARCHAR(250) NOT NULL,
+  "status" INTEGER,
+  "created" DATETIME NOT NULL,
+  "signed" DATETIME,
+  CONSTRAINT "name"
+    UNIQUE("name")
+);
+
+CREATE TABLE "users_roles"(
+  "rid" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL CHECK("rid">=0),
+  "role" VARCHAR(100) NOT NULL,
+  CONSTRAINT "role"
+    UNIQUE("role")
+);
+
+CREATE TABLE "nodes"(
+  "nid" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL CHECK("nid">=0),
+  "version" INTEGER,
+  "type" INTEGER,
+  "title" VARCHAR(255) NOT NULL,
+  "summary" TEXT NOT NULL,
+  "content" MEDIUMTEXT NOT NULL,
+  "author" INTEGER,
+  "publish" DATETIME,
+  "created" DATETIME NOT NULL,
+  "changed" DATETIME NOT NULL
+);
+COMMIT;