New example: voltage clamp

[AurelienJaquier]

Description

New example: voltage clamp with data from channelpedia and jupyter notebook

Checklist:

• Unit tests are added to cover the changes (skip if not applicable).
• The changes are mentioned in the documentation (skip if not applicable).
• CHANGELOG file is updated (skip if not applicable).

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 90.83333% with 11 lines in your changes missing coverage. Please review.

Project coverage is 92.22%. Comparing base (2cddd26) to head (1c765be).
Report is 31 commits behind head on master.

Files	Patch %	Lines
efel/pyfeatures/pyfeatures.py	84.37%	10 Missing ⚠️
tests/test_pyfeatures.py	98.07%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #408      +/-   ##
==========================================
+ Coverage   91.73%   92.22%   +0.48%     
==========================================
  Files          36       39       +3     
  Lines        6278     7509    +1231     
  Branches     2033     2297     +264     
==========================================
+ Hits         5759     6925    +1166     
- Misses        266      300      +34     
- Partials      253      284      +31     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[AurelienJaquier]

I also added fitting curves to the plot of the example as requested by @darshanmandge in latest commit

[darshanmandge]

Thanks @AurelienJaquier !

[ilkilic]

Thank you @AurelienJaquier !