Generate new-style sourcemap comment and improved regexes

The sourcemap comment now use # instead of @ as propose the new
specification.

The regexes now detect both old and new sourcemap comment styles and
also they work in a per-line basis, allowing a cleaner code and also
preventing ana managing correctly bugs like
https://github.com/substack/node-browserify/issues/540
Merge branch 'master' of github.com:piranna/minifyify