Move everything under kotlin-native folder

I was forced to manually do update the following files, because otherwise
they would be ignored according .gitignore settings. Probably they
should be deleted from repo.

Interop/.idea/compiler.xml
Interop/.idea/gradle.xml
Interop/.idea/libraries/Gradle__org_jetbrains_kotlin_kotlin_runtime_1_0_3.xml
Interop/.idea/libraries/Gradle__org_jetbrains_kotlin_kotlin_stdlib_1_0_3.xml
Interop/.idea/modules.xml
Interop/.idea/modules/Indexer/Indexer.iml
Interop/.idea/modules/Runtime/Runtime.iml
Interop/.idea/modules/StubGenerator/StubGenerator.iml
backend.native/backend.native.iml
backend.native/bc.frontend/bc.frontend.iml
backend.native/cli.bc/cli.bc.iml
backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2Native.kt
backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2NativeCompilerArguments.kt
backend.native/tests/link/lib/foo.kt
backend.native/tests/link/lib/foo2.kt
backend.native/tests/teamcity-test.property

kotlin-native/backend.native/tests/codegen/function/sum.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package codegen.function.sum
+
+import kotlin.test.*
+
+fun sumIB(a:Int, b:Byte  ) = a + b
+fun sumIS(a:Int, b:Short ) = a + b
+fun sumII(a:Int, b:Int   ) = a + b
+fun sumIL(a:Int, b:Long  ) = a + b
+fun sumIF(a:Int, b:Float ) = a + b
+fun sumID(a:Int, b:Double) = a + b
+
+fun modID(a:Int, b:Double) = a % b
+
+@Test fun runTest() {
+    if (sumIB(2, 3)    != 5)    throw Error()
+    if (sumIS(2, 3)    != 5)    throw Error()
+    if (sumII(2, 3)    != 5)    throw Error()
+    if (sumIL(2, 3L)   != 5L)   throw Error()
+    if (sumIF(2, 3.0f) != 5.0f) throw Error()
+    if (sumID(2, 3.0)  != 5.0)  throw Error()
+    if (modID(5, 3.0)  != 2.0)  throw Error()
+}