Replace deprecated get_column_view

[markotoplak]

The replacement, get_column, also takes care of the conversion into the correct data type.

[markotoplak]

@stuart-cls, look, simpler averaging. :) Thanks to biolab/orange3#6058

[codecov-commenter]

Codecov Report

Merging #645 (a5529a4) into master (5203f9f) will increase coverage by 0.05%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #645      +/-   ##
==========================================
+ Coverage   89.28%   89.34%   +0.05%     
==========================================
  Files          71       71              
  Lines       11818    11818              
==========================================
+ Hits        10552    10559       +7     
+ Misses       1266     1259       -7     

[stuart-cls]

@markotoplak Excellent! Thanks for pointing it out, I reach for the get_column_view often in scripts: this is much nicer to use.

I also love changes that get rid of long explanatory comments :D