[ogalias] introduces dependence in bulk generation

Hi and many thanks for this great module!

Problem

My default alias pattern is [ogalias]/[type-name]/[title-raw].
My OG alias pattern is [title-raw].

When re-generating all my aliases, I found that the [ogalias] token might not yet be ready.
I got ugly URLs like http://example.com/node/123/story/intro-to-the-group-of-insiders, instead of http://example.com/insiders/story/intro-to-the-group-of-insiders, because the group's alias was not yet generated.

Proposed resolution

Forcing the regeneration process on all groups first (through an empty default alias pattern), and only afterwards assign aliases to group content solves the issue manually, but not elegantly.

When using other nodes' aliases through [...alias] tokens, we need their alias generated, first. This implies a dependence graph. I'm afraid that this graph might have circles. Please prove me wrong!

Max