Add source maps support.
Refactor source maps code.
Merge branch 'refs/heads/master' into topics/source-maps

Conflicts:
	package.json
FUCKING SOURCE MAPS YES
fix source maps for non-commonjs configurations

this method allows custom wrapper functions to work the same way as before (i.e. without special source node handling)
Merge pull request #562 from es128/fix-sourcemaps

fix source maps for non-commonjs configurations
Add adequate errors for npm install req.
Merge branch 'master' of github.com:brunch/brunch
Fix typo.
Merge remote-tracking branch 'upstream/master'