ADD: User authentication

* User Authentication Implementation
* Rename file to conform to fileformat `sqlite3_*_omit.go`
* Updated sqlite3-binding.* with new upgrade tool
* Add: callbackRetNil required for error type return because of adding `RegisterFunc`s directly on the connection.
* Add: TestCreateAuthDatabase

sqlite3_opt_userauth_omit.go

@@ -0,0 +1,65 @@
+// Copyright (C) 2018 G.J.R. Timmer <gjr.timmer@gmail.com>.
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+// +build !sqlite_userauth
+
+package sqlite3
+
+import (
+	"C"
+)
+
+// Authenticate will perform an authentication of the provided username
+// and password against the database.
+//
+// If a database contains the SQLITE_USER table, then the
+// call to Authenticate must be invoked with an
+// appropriate username and password prior to enable read and write
+//access to the database.
+//
+// Return SQLITE_OK on success or SQLITE_ERROR if the username/password
+// combination is incorrect or unknown.
+//
+// If the SQLITE_USER table is not present in the database file, then
+// this interface is a harmless no-op returnning SQLITE_OK.
+func (c *SQLiteConn) Authenticate(username, password string) error {
+	// NOOP
+	return nil
+}
+
+// AuthUserAdd can be used (by an admin user only)
+// to create a new user.  When called on a no-authentication-required
+// database, this routine converts the database into an authentication-
+// required database, automatically makes the added user an
+// administrator, and logs in the current connection as that user.
+// The AuthUserAdd only works for the "main" database, not
+// for any ATTACH-ed databases. Any call to AuthUserAdd by a
+// non-admin user results in an error.
+func (c *SQLiteConn) AuthUserAdd(username, password string, admin bool) error {
+	// NOOP
+	return nil
+}
+
+// AuthUserChange can be used to change a users
+// login credentials or admin privilege.  Any user can change their own
+// login credentials.  Only an admin user can change another users login
+// credentials or admin privilege setting.  No user may change their own
+// admin privilege setting.
+func (c *SQLiteConn) AuthUserChange(username, password string, admin bool) error {
+	// NOOP
+	return nil
+}
+
+// AuthUserDelete can be used (by an admin user only)
+// to delete a user.  The currently logged-in user cannot be deleted,
+// which guarantees that there is always an admin user and hence that
+// the database cannot be converted into a no-authentication-required
+// database.
+func (c *SQLiteConn) AuthUserDelete(username string) error {
+	// NOOP
+	return nil
+}
+
+// EOF