Generates empty file (*.type) when creating inline sourcemap

[Alexander Tikvach]

https://github.com/enb-make/enb-stylus/blob/master/techs/stylus.js#L334

if (this._sourcemap && !this._sourcemap.inline) {

fix:

if (this._sourcemap && this._sourcemap !== 'inline') {

[Andrew Abramov]

Fixed in #104