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/jsinterop/math.kt

@@ -0,0 +1,21 @@
+/*
+ * 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.
+ */
+
+import kotlinx.interop.wasm.math.*
+import kotlinx.wasm.jsinterop.*
+
+fun main(args: Array<String>) {
+
+    val e = Math.E
+    val pi = Math.PI
+
+    val sin_pi = Math.sin(pi)
+    val sin_pi_2 = Math.sin(pi/2)
+    val ln_1 = Math.log(1.0)
+    val ln_e = Math.log(e)
+
+    println("e = $e, pi = $pi, sin(pi) = $sin_pi, sin(pi/2) = $sin_pi_2, ln(1) = $ln_1, ln(e) = $ln_e")
+}
+