Remove the points added oustide of a mask. Fix the related tests.

[czotti]

This PR is to address the issue #1661.
I recreate a PR because I made a mistake during the rebase.

• It change the way points are added to a streamline if the point is outside the mask.
• I changed all the needed test.

[codecov-io]

Codecov Report

Merging #1666 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1666      +/-   ##
==========================================
- Coverage   84.27%   84.26%   -0.01%     
==========================================
  Files         115      115              
  Lines       13606    13606              
  Branches     2144     2144              
==========================================
- Hits        11466    11465       -1     
  Misses       1643     1643              
- Partials      497      498       +1

Impacted Files	Coverage Δ
dipy/core/graph.py	73.8% <0%> (-1.2%)	⬇️

[guaje]

Thanks, @czotti for your contribution. We're going to merge these changes.

[skoudoro]

+1, Thanks @czotti, Can you rebase this PR before I merge it

[czotti]

One test failing because it's unable to get python 3.5 from s3: https://s3.amazonaws.com/travis-python-archives/binaries/ubuntu/14.04/x86_64/python-3.5.tar.bz2

The second fails is due to Cython unable to compile: dipy.tracking.fbcmeasures.

As far as I know, it's not related to my commit no?

[skoudoro]

One test failing because it's unable to get python 3.5 from s3

I just restarted this build

As far as I know, it's not related to my commit no?

No, it is not related, DIPY is failing with the future Cython release, we have to fix it.

[skoudoro]

Merging, Thank you @czotti