Parse multi-line __future__ imports better

[akx]

Augments #426
Augments #427
Augments #510
Closes #510

[codecov-io]

Codecov Report

Merging #519 into master will decrease coverage by 1.35%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #519      +/-   ##
==========================================
- Coverage   90.18%   88.83%   -1.36%     
==========================================
  Files          24       24              
  Lines        4015     4020       +5     
==========================================
- Hits         3621     3571      -50     
- Misses        394      449      +55

Impacted Files	Coverage Δ
babel/util.py	90.78% <100%> (-1.05%)	⬇️
babel/_compat.py	53.48% <0%> (-46.52%)	⬇️
babel/localtime/_unix.py	11.53% <0%> (-20.52%)	⬇️
babel/localtime/_win32.py	59.25% <0%> (-3.71%)	⬇️
babel/localtime/__init__.py	62.5% <0%> (-2.5%)	⬇️
babel/messages/catalog.py	92.23% <0%> (-2.39%)	⬇️
babel/messages/extract.py	94.18% <0%> (-1.1%)	⬇️
babel/localedata.py	94.64% <0%> (-0.9%)	⬇️
babel/support.py	82.28% <0%> (-0.4%)	⬇️
... and 1 more

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[akx]

@sublee, care to take a look? :)

[sublee]

@akx Looks better.

I suggest you to add more multi-line import styles for unit testing:

from __future__ import (
    print_function,
    division)

from __future__ import \
    print_function, \
    division

[akx]

@sublee Thanks! Excellent points -- neither of those cases actually worked. They do now! :)