More end points for REST API please!!

[AL B]

The REST API is great but fairly restricted. Can we not have this added:

GET /core/members/{email}

In the file applications/core/api/members.php we have:

	public function GETitem( $id )
	{
		try
		{
			$member = \IPS\Member::load( $id );

This could be changed to:

	public function GETitem( $id )
	{
		$idField = filter_var( $id , FILTER_VALIDATE_EMAIL ) ? 'email' : 'member_id';
		try
		{
			$member = \IPS\Member::load( $id, $idField );