Add Kotlin asset support

[Zoweb]

↪️ Pull Request

This should close #2177 by adding support for Kotlin. Unfortunately, the only possible way to implement Kotlin support was to use the compiler, which can only generate files, so a temporary directory is created and deleted with those files, if there is nothing else in it.

Running Kotlin functions from other languages (e.g. importing a Kotlin file in a JavaScript file, then running a function defined in it) doesn't work as intended - the Kotlin compiler adds some extra text to the function names, which has to be added in the other language as well.

To get Kotlin code to run automatically, instead of just putting the code directly in the file, create a fun main(args: Array<String>). This function will be called with an empty list of arguments.

Note that the Kotlin standard library is included in the result, and is huge. Building in production mode minifies the source but it is still over 600KB with the test described below. Implementing treeshaking may help, if this is not already done.

🚨 Test instructions

Create an index.html file and a test.kt file. Add a <script> tag with the src pointing to the kt file.

Inside the Kotlin file, add the following code:

fun main(args: Array<String>) {
    for (i in 0 until 100) {
        if (i % 20 == 0) print("FooBar")
        else if (i % 5 == 0) print("Bar")
        else if (i % 4 == 0) print("Foo")
        else print(".")

        println(" [$i]")
    }
}

This should print 100 lines, where every 4th is "Bingle [(line num)]", 5th is "Foo [(line num)]", 20th is "FooBar [(line num)]" and every other line is ". [(line num)]"

✔️ PR Todo

• Added/updated unit tests for this change
• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs

[Zoweb]

Hmm, it looks like elm failed but just on Windows/Node 6

[devongovett]

Can you use the path library for this? It will take care of the normalization cross platform for you.

[devongovett]

You should be explicit about exactly where this is going to go. Right now it will go into the current working directory. Instead, it would be better to go into a temporary directory.

[devongovett]

This is awesome! It would be great if you could add some tests.

[Zoweb]

Oh thanks for doing those changes! I only saw this yesterday, so hadn't had time to do it yet.