Extended version of module to include user domain categories

For a recent project, we had to extend this module. We wanted to assign users to a personal website, but also connect them to a country website. Hence we extended the module so that you could create multiple categories of user <-> domain relationship

By default, there is one 'Personal website' category created, just like the current version of the module. When you add more categories, you can choose under which category a domain will be automatically created for a registering user, and also use the category to determine the domain a user will be directed to upon login.

The module also comes with Views relationship handlers so you can present listings of users, connected to domains via different categories. You can even connect the different categories of domains together through their mutual users (for example on a country site, you could show content created by users on their member websites).

I am attaching my work here. Note that the module is still only Domain Access 2.x compatible, and would therefore need a little work before a release. I would be happy to co-maintain this module.