Inline source maps

An implementation for #199 - inline source maps.

The generated source map is inlined as `data:application/json` url.

Additionally as https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit suggest the url (inline or not) should be url encoded.