This document tries to explain the rights management.

We have a table for all rights types.
There are types for user, repo, refs etc.

The table has the following fields:
	right_id - auto increment field, needed for editing and deletion.
	rights - text, one letter means one right
	misc, misc2: these are used for refs and path for 'refs' type.
		Other types may used these fields.
	who - Who gave the rights (uid).
	prio - Priority of the right (for evaluation ascending ordering)
	uid - uid of the user that the rights were granted to.
	obj_id - opaque id of a resource. It may be the repo_id or the user_id.

We have some function to manage the rights:
-rg_rights_set($db, $right_id, $who, $type, $obj_id, $uid, $rights,
	$misc, $ip, $prio)
	Sets the rights for a type-uid-obj_id combination.

- rg_rights_load($db, $type, $obj_id)
	Loads all rights for an object, identified by
	type and obj_id; type may be '*' for all rights type.

- rg_rights_delete_list($db, $type, $obj_id, $list)
	Deletes a list of rights,
	obtained by selecting them in the form.