390 standalone debug

This is to fix #390. I'm not actually sure what OP was reporting as problematic, but the only problems I observe are a problem with source map alignment.

I did something presumptuous and added a package.json bump for substack/browser-pack.

It assumes substack/browser-pack#23 merge, and subsequent version bump.

Tests pass here and in browser-pack.

In my testing, I'm having no issues using these options together with `browserify.bundle()`.