Continental Update

A pretty small update but possibly substantial.  I've added an optional rule to give players an option to combine islands in Era 1 to create some larger landmasses, or even start with a massive continent shared between all home regions.

I've also renamed Minor Factions to Minor Kingdoms.  I don't want to force the idea of them necessarily being a kingdom, but I wanted to emphasize that every entity in the world is a "faction" (including hives, monsters, and cults) and I think that might have been a bit confusing before.