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/samples/coverage/README.md

@@ -0,0 +1,12 @@
+# Code Coverage usage sample
+
+This example shows how to collect coverage information during execution of the test suite. 
+Please note that this functionality will be incorporated into Gradle plugin so you won't need to do it by hand in the nearest future. 
+
+### Prerequisites
+`createCoverageReport` task requires `llvm-profdata` and `llvm-cov` to be added to the `$PATH`. 
+They can be found in the Kotlin/Native dependencies dir. By default it should look like
+`$HOME/.konan/dependencies/clang-llvm-6.0.1-darwin-macos/bin`
+
+### Usage
+Just run `createCoverageReport` task.