Issue 1087 endpoints interpolate 2D

[brosaplanella]

Description

Fixed the interpolator for 2D processed variables so it can be evaluated at the boundaries of the domain.

Fixes #1087

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ flake8
• All tests pass: $ python run-tests.py --unit
• The documentation builds: $ cd docs and then $ make clean; make html

You can run all three at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

Merging #1088 into develop will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop    #1088   +/-   ##
========================================
  Coverage    97.77%   97.78%           
========================================
  Files          242      242           
  Lines        12643    12660   +17     
========================================
+ Hits         12362    12379   +17     
  Misses         281      281           

Impacted Files	Coverage Δ
pybamm/parameters/parameter_sets.py	100.00% <ø> (ø)
pybamm/solvers/processed_variable.py	99.61% <100.00%> (+0.02%)	⬆️
pybamm/solvers/solution.py	99.28% <100.00%> (+<0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cc5d9f1...2d5f326. Read the comment docs.

[valentinsulzer]

Great! And thank you for also fixing the points for the 2D plots :)