add missing preprocessor guard around coroutine dependant code in generic generator utility function

add "--failfast" (stop on first failure) mode to test runner (if supported by Python's unittest module)

refactor "yield from" and "await" nodes a little to provide a cleaner split between them (await nodes are not yield-from nodes)

allow "args" tuple argument to be NULL in __Pyx__Coroutine_Throw() and only create a tuple if necessary

clean copy of the current AsyncGen implementation proposed for CPython 3.6 to make local changes visible

Remove a macro from helper code that I find difficult to read. The result is not perfect, but at least it's more visible what get's assigned to what.

use pre-instantiated strings in __Pyx_setup_reduce() to reduce overhead - we will most likely need and indefinitely store them in the types anyway

This fixes #1798.

Suppress special casing of attribute names in closure classes since they are not user defined and any local variable name is allowed without being special.

Closes #1797.

This reverts commit b4fbd9bc.

emacs: use "" as buffer name in indirect buffers