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/test0.kt

@@ -0,0 +1,9 @@
+val TOP_LEVEL = 5
+
+enum class MyEnum(value: Int) {
+    VALUE(TOP_LEVEL)
+}
+
+fun main(args: Array<String>) {
+    println(MyEnum.VALUE.toString())
+}