add csv syntax highlighting in template

[mashehu]

Will look something like this:

[codecov]

Codecov Report

Merging #2503 (82a355d) into dev (3fddb70) will decrease coverage by 0.03%.
Report is 29 commits behind head on dev.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev    #2503      +/-   ##
==========================================
- Coverage   70.53%   70.50%   -0.03%     
==========================================
  Files          87       88       +1     
  Lines        9456     9515      +59     
==========================================
+ Hits         6670     6709      +39     
- Misses       2786     2806      +20     

see 12 files with indirect coverage changes

[ewels]