Add Kotlin backend (#270)

Author: epost

ecosystem/Alternate-backends.md

@@ -12,6 +12,7 @@ There are various alternatives to `psc`'s default JavaScript backend:
 | source code                                                                             | PS version | Target        | 
 |:----------------------------------------------------------------------------------------|:-----------|:--------------|
 | [andyarvanitis/purescript-clojure](https://github.com/andyarvanitis/purescript-clojure) |            | Clojure (JVM) |
+| [csicar/pskt](https://github.com/csicar/pskt)                                           |            | Kotlin        |
 | [pure-c/pure-c](https://github.com/pure-c/pure-c)                                       |            | C (Clang)     |
 | [epost/psc-query](https://github.com/epost/psc-query)                                   | 0.11.7     | Datalog       |
 | [tfausak/thran](https://github.com/tfausak/thran)                                       | 0.11.6     | Haskell (GHC) |