Fix for rules within media queries (plus overall cleanup and documentation)

* Implemented fix to parse style rules within media queries
* Moved from `base_path` configuration param to an `options` object (backward-compatible)
* Refactored main method as multiple smaller functions
* Refactored function expressions as declarations for more informative stacktraces
* Lint cleanup
* Added JSDoc comments
* Updated contributors
* Version bump
`args` was previously unused. Passing it to the exported `svg` function.