Check if user's class methods are coroutines in Async mode
Closes #514 (closed)
I cannot find any option to fix it to "just work", since we automatically wrap BaseClass methods happens already at the import, so all its standard methods are coroutines.
I propose, that we just check, if methods in user class are coroutines and trow an warning, if they are not
Edited by Yury Matveyev