Implements Automatic Paths

Contains three main points;

1. Deletes the pointless extension `implement` headers
2. Commits the fix for the extension system's variable access
   - From now on, use `enigma::extension_cast::as_your_extension_class(inst)` to cast.
   - Declare this yourself as you need it.
   - See the path and alarm sources for an example.
3. Fixes paths; `path_start` now begins and updates the path correctly.