add logic to `.lookup()` method to search with or without ext
Merge remote-tracking branch 'origin/master'
revert .lookup()
start adding docs
move files to recipes
move recipes to docs
removes `.context()` method, moves logic to `.mergeContext()`.

  - Also changes extend to merge in some places
  - adds code comments
allow a custom `.mergePartials()` function to be defined
revert `ctx` to `context`. will make related prs next.
remove duplicate ext logic from `.engine()`