Support TypeScript 2.3

[JamesHenry]

TypeScript 2.3 was recently released as the latest stable version and we should look to support it as soon as possible.

On initial inspection of a broken build, it looks like JSX will be the main area of focus for changes.

[soda0289]

We will also need to support async iterators as well. I think we can just use a flag on the for loop node.

[soda0289]

I can look into the JSX issues unless @azz is already working on it.
I see this already fixed. Thanks @azz

[terrierscript]

Thank you for fixing. I want use this with ts 2.3.
Is this fix is released? (or When is this fix published?)

[soda0289]

@inuscript We have typescript 2.3 support in the master branch. We are currently working towards releasing a new major version, v3. Not sure exactly on time frame of new release but should be fairly soon.