WME Lite completely.
(This also breaks compatibility with savegames from ScummVM prior to this commit, AND resets the
Savegame-version, older savegames will have differing MAGIC-numbers in their headers, and will thus
not be recognized).
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.