implement package synchronization and validation; update database schema and add error handling

doc/indexdbSchema.txt

@@ -13,5 +13,23 @@ CREATE TABLE packages(
     family          TEXT NOT NULL,
     arch            TEXT NOT NULL,
     os              TEXT NOT NULL,
+    size            INTEGER NOT NULL DEFAULT 0,
+    serial          INTEGER NOT NULL
+);
+
+
+CREATE TABLE IF NOT EXISTS packages (
+    query_name      TEXT NOT NULL,
+    name            TEXT NOT NULL UNIQUE PRIMARY KEY, 
+    version         TEXT NOT NULL, 
+    dependencies    TEXT NOT NULL DEFAULT '', 
+    description     TEXT NOT NULL,
+    family          TEXT NOT NULL,
+    serial          INTEGER NOT NULL UNIQUE, 
+    package_d       TEXT NOT NULL,
+    filename        TEXT NOT NULL,
+    os              TEXT NOT NULL,
+    arch            TEXT NOT NULL,
+    in_cache        INTEGER NOT NULL DEFAULT 1,
     serial          INTEGER NOT NULL
 );