Scatter Plot: Error Bars

[VesnaT]

Issue

Add Error Bars to points.

Closes #6428.

Description of changes

• introduce a dialog for variable selection
• add error bars to plot

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Attention: Patch coverage is 97.31183% with 5 lines in your changes missing coverage. Please review.

Project coverage is 88.47%. Comparing base (c2c1648) to head (026e4f7).
Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6934      +/-   ##
==========================================
+ Coverage   88.45%   88.47%   +0.02%     
==========================================
  Files         331      332       +1     
  Lines       73099    73272     +173     
==========================================
+ Hits        64659    64829     +170     
- Misses       8440     8443       +3     

[janezd]

I had to change glasses to see what's actually in the button.

If any, I think it should be delta, not epsilon. But what I had in mind would be an icon like this.

It takes a bit more space (which I'm sorry for), but it's better to take space that to look weird. :)

I'd also slightly modify the dialog, like this:

I think it was not very clear what "Difference" and "Absolute" meant. Now it may be a bit better, though a tooltip would help.

One minor comment: "Upper" and "Lower" make more sense for y. For x, the order is also weird -- there I'd expect to set the lower limit first.

I cannot push a new commit to this PR, so I'm attaching a diff and the icons.

interval-horizontal
interval-vertical
addicons.patch