Add enumeration support. (#128)

* Add enumeration support.

* Enum classes lowering.

* merge fix

* merge fix

* used arrayOf from irModule

* changed lowering quant from body to file

* refactoring

* review fixes

* lowering for GET_OBJECT in enums

* enabled tests

* added tests

* moved tests to separate dir

* renamed test files

* moved phase up

* review fixes

* reformat

backend.native/tests/codegen/enum/test1.kt

@@ -0,0 +1,8 @@
+enum class Zzz(val zzz: String, val x: Int) {
+    Z1("z1", 1),
+    Z2("z2", 2)
+}
+
+fun main(args: Array<String>) {
+    println(Zzz.Z1.zzz + Zzz.Z2.x)
+}