Clearly mark the test() method that it crosses the test boundaries

[mvysny]

There is no clear distinction between the code that creates tests (calls the test() method), and
the testing code itself (blocks inside of test() method). However, there is a ton of difference:
those two code bases run at completely different time. Furthermore Kotlin allows to share variables
freely between those two code bases, which may create a really dangerous code which fails in mysterious ways.

That's magic which must be removed. The test() method must yell a big warning sign that the programmer is crossing code boundaries. I'm thinking about renaming the test() method to something else, but I'm not really satisfied with any of the candidates:

• post() - not really a test
• postTest() - too long
• marking test() deprecated - stupid :-)