I apparently wasn't following exactly what Obsidian was doing. This
algorithm is getting a bit complex and should be documented, also now
I'm not sure how other apps are doing it, and maybe I should have
specific link resolvers per 'app'.
Fixes#212
With this [[Fire]] will always resolve the rootFolder/Fire.md
irrespective of which note it appears in. This is analogous to the way
Obsidian works.