Fix dynamic cache

This fixes dynamic cache by having one dynamic cache per `[path +
options.external + options.debug]` combo
Merge pull request #37 from ForbesLindesay/fix/dynamic-cache

Fix dynamic cache
Update browserify to 3.24.1
Release 2.3.0
Introduce precompile option
Enable cache in example code
Fix messed up diffs and remove call to path.resolve