subuser 6.x-1.3

- Changes:
* #459694: Limit number of subusers: Adds a configurable limit to the number of subusers a particular user can create.
* #942660: Add relationship for views to access parent user data: Adding a relationship for views to access parent user data.
* #726914: Subuser perm related issues: Cleanup subuser permission related issues for edit and switch links. Add custom views handlers for edit and switch links.
* #681962: Allow changes to parent user to cascade to subusers: Allow changes to parent user to cascade to subusers. Provides configuration on the settings form for Blocked/Unblocked status and Role changes to propagate to subusers. Also includes configuration for what to do with orphaned subusers when the parent user is deleted.
* #1058708: use url for create new role link: Fixes hard coded link to /admin/user/roles in favor or url()
* #555798: does not follow namespace with user_relationship tablename: Changes db table from user_relationship to subuser_relationship.
* #600390: Create subuser doesn't deny access to non-parents: Fixes create subuser logic so permissions actually work.
* Allow a specific role to be exempted from the cascading behavior.
* Allow the number of subusers to be set per-user rather than just site-wide.