MRG: Add nirs support to plot_evoked_topo

[rob-luke]

Reference issue

Adding general NIRS support #7057

What does this implement/fix?

Allows plotting of evoked topo map for nirs data

[rob-luke]

@larsoner could you please review. The function now behaves as I would expect. The CI errors seem unrelated to the code changes.

[agramfort]

LGTM https://18396-1301584-gh.circle-artifacts.com/0/dev/auto_tutorials/preprocessing/plot_70_fnirs_processing.html#sphx-glr-auto-tutorials-preprocessing-plot-70-fnirs-processing-py

it seems travis failures are unrelated.

[codecov]

Codecov Report

Merging #7408 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #7408      +/-   ##
==========================================
+ Coverage   90.01%   90.03%   +0.01%     
==========================================
  Files         453      454       +1     
  Lines       82233    82214      -19     
  Branches    13012    13002      -10     
==========================================
- Hits        74023    74022       -1     
+ Misses       5384     5368      -16     
+ Partials     2826     2824       -2     

[rob-luke]

Sorry to modify this after you approved @agramfort
But I realised I had repeated some code that will probably be common as I add more nirs tests, so I have created a helper function to generate the data. Let me know if you want me to revert this change.

[larsoner]

LGTM +1 for merge with or without my pytest enhancement. @rob-luke I'll let you decide whether or not to do it, depends on how much you want to dig into pytest magic :)

[rob-luke]

Ok don’t merge. And I will try this fancy pytest stuff.

[rob-luke]

Thanks @larsoner I think I have implemented your suggestion. Can you please review again.

[larsoner]

Thanks @rob-luke !