[ENH] New signals: Trees, Forest

[jerneju]

Issue

Fixes #2797

Description of changes

Tree Viewer
Pythagorean Tree
Pythagorean Forest
Geo Map

Includes

• Code changes
• Tests
• Documentation

[codecov-io]

Codecov Report

Merging #2801 into master will increase coverage by <.01%.
The diff coverage is 98.31%.

@@            Coverage Diff             @@
##           master    #2801      +/-   ##
==========================================
+ Coverage   76.16%   76.17%   +<.01%     
==========================================
  Files         338      338              
  Lines       59879    59910      +31     
==========================================
+ Hits        45606    45635      +29     
- Misses      14273    14275       +2

[nikicc]

Looks good to me.

Though, I have one minor comment. IMHO
self.widget.Inputs.tree
is better, cleaner and not that much longer than

w = self.widget
w.Input.tree

But it might be just a personal preference.

[nikicc]

@lanzagar I suggest we merge this, if you still allow merging before the release.

[lanzagar]

I agree introducing another variable and line of code is often not worth it just to save a few characters in a couple of lines after that. But it is a matter of preference and not a big issue so I would prefer not to wait with merging until the last minutes before a release.