Cannot resolve ForwardRef if from __future__ import annotation is used.

[hanjinliu]

In a .py file, the type matcher fails to convert simple types (int, str, ...) into widgets if the file starts with from __future__ import annotation.

from __future__ import annotation
from magicgui import magicgui

@magicgui
def f(i: int):
    pass

Looks like it is because int is converted into "int". Additional matching system is needed.