Docs fix

- fix caching (I had a `loadDocs.reset()` used incorrectly, refactored so all submodules are in cache)
- fix sidebar that was missing some methods (fixes #129)
@ibolmo the docs source have it: https://github.com/mootools/mootools-core/blob/master/Docs/Core/Core.md#type-core-core and it's not needed here.