Removes all tight_layout calls

Matplotlib offers constrained layouts:

https://matplotlib.org/stable/tutorials/intermediate/constrainedlayout_guide.html

which performs better than tight layouts:

https://github.com/matplotlib/cheatsheets/issues/30#issuecomment-655594205

At the same time, tight layout is known to trigger certain bugs. For example:

https://github.com/matplotlib/ipympl/issues/335

Here we remove all call to tight_layout in the toolbox. @carinanc @mercurio

doc/changelog.rst

@@ -9,6 +9,7 @@ unreleased
 
 - **Improvements**
 
+    - remove calls to matplotlib tight_layout :mr:`206`
 
 - **New Features**