Fix typo
Make path stripping optional in `.extract()`

Fixes #664.
Fix code inconsistencies in tests
Proof of Concept: fix generator.invoke

Create a new `runLoop` for the invoked generator.
Fix Base#hookFor() method and cleanup invoke fix

Add Environment#duplicate() to create performant copy of a complete
environment.
Remove unecessary use strict statement
Notify the user when changing the scaffolding root directory
0.17.7