[FIX] Paint Data: Send correct output after clicking Reset to Input

[aturanjanin]

Issue

Fixes #4514.

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #4551 into master will increase coverage by 0.15%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #4551      +/-   ##
==========================================
+ Coverage   83.37%   83.53%   +0.15%     
==========================================
  Files         279      276       -3     
  Lines       55779    55233     -546     
==========================================
- Hits        46507    46138     -369     
+ Misses       9272     9095     -177     

[lanzagar]

PR titles (with tags) are used to automatically compile the CHANGELOG.
Users will probably not know what changed when seeing this one in the list of changes.
Maybe something like:
[FIX] Paint Data: Send correct output after clicking Reset to Input
(or something better if anyone has a suggestion)

p.s. commit messages can be more technical as they are intended for developers.
An improvement for this one could be:
"OWPaintData: commit after reset_to_input()"

[aturanjanin]

@lanzagar Thanks for your suggestions, I will fix this now.