This is helpfull for consistency between registering and lookup, and allows for explicit removal/adding
of sub_paths for the engine. But most importantly it keeps the loading consistent and non-duplicated
for detection.
This is mostly a lead-up to namespacing the Ad/Base folders, and then
possibly removing the prefixes from the files, it also has the added
benefit of getting rid of the odd case-typos that makes for issues
on platforms that don't ignore case.
Einar Johan Trøan Sømåen