Engines meet their Builder

- bump to version 0.0.3
- engines now can read and write to Builder freely
- remove pre-defined and generic options object
- this increases flexibility but removes per-engine sandbox
- hint public and private variables within Builder
- permit before/after hooks to transform local variables, track
included files, etc.
req.files

- store files in request object
- rename includes to files in Builder
- also, disable swig caching