Thanks to [bpo-32489](https://bugs.python.org/issue32489) and sadly
for rejection of my [PEP 601](https://www.python.org/dev/peps/pep-0601/)
finally in continue is supported in 3.8+. I checked the blame and looks
like there was already a commit for the same subject, but that only
changes the test and not actually changes the checker (dfe7fba08e)
PEP 563 brought a new `__future__` import for post-poning evaluation
of annotations that introduced in 3.7. This patch adds support for
that future feature, and removes 'all_feature_names' from that list
since it is not valid a syntax
(`from __future__ import all_feature_names`). Also it fixes a bug
related usage of `ALLOWED_FUTURES` (global and version independant
flags) instead of `allowed_futures` (extended version of the previ
ous flag that has some version specific flags, probably unnoticed)
Batuhan Taskaya