[FIX] Paint Data: now stores data in list and not np.array

[jerneju]

Issue

https://sentry.io/biolab/orange3/issues/240133185/

Steps to reproduce the behavior

One way to reproduce this behavior:
Use Paint Data widget and draw some points. Then save it. Close the Orange. Open the Orange and then load the file and close the Orange again. Error should be thrown.

These steps were tested in Orange versions master, 3.4.2, 3.4.1 and 3.3.12. In all those versions error occurred.

Includes

• Code changes
• Tests
• Documentation

[jerneju]

https://sentry.io/biolab/orange3/issues/240133185/

[astaric]

How can the error be reproduced by user? (= not in code)?

[jerneju]

@astaric : Now added above.

[codecov-io]

Codecov Report

Merging #2314 into master will increase coverage by 0.04%.
The diff coverage is 84.61%.

@@            Coverage Diff             @@
##           master    #2314      +/-   ##
==========================================
+ Coverage   73.27%   73.31%   +0.04%     
==========================================
  Files         317      317              
  Lines       55447    55452       +5     
==========================================
+ Hits        40630    40656      +26     
+ Misses      14817    14796      -21

[jerneju]

Changed Paint Data. Now stores points in List. Therefore settings are saved in literal format and not pickle.