Support executing suspend functions directly

[soywiz]

Right now you have to call runBlocking { } manually, and it would be nice if that is not required

[ileasile]

Hi, @soywiz! It's now not available in Kotlin scripting, on which kernel is based on: https://youtrack.jetbrains.com/issue/KT-23212
Please keep track of this issue.

[altavir]

What is possible is to add a renderer for Job and Deferred objects, which invokes runBlocking under the hood. It is also possible to add a Notebook-wide scope instead of Global and add a top-level launch extension. It was briefly discussed in #239. I can implement the corresponding plugin if anybody is interested.