Add Swift Package support

For xcode 11: this will be very useful.
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<img width="748" alt="Снимок экрана 2019-09-22 в 11 49 39" src="https://user-images.githubusercontent.com/1159547/65384821-a3a1c480-dd2f-11e9-9e47-f40bfb41bc86.png">
