Improve diagnostic output of pde.PDE

[codecov[bot]]

Codecov Report

Base: 87.64% // Head: 87.70% // Increases project coverage by +0.06% :tada:

Coverage data is based on head (8654c50) compared to base (3e493ea). Patch coverage: 83.15% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #315 +/- ## ========================================== + Coverage 87.64% 87.70% +0.06% ========================================== Files 69 69 Lines 10350 10390 +40 ========================================== + Hits 9071 9113 +42 + Misses 1279 1277 -2 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `87.70% <83.15%> (+0.06%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://codecov.io/gh/zwicker-group/py-pde/pull/315?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group) | Coverage Δ | | |---|---|---| | [pde/pdes/pde.py](https://codecov.io/gh/zwicker-group/py-pde/pull/315/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group#diff-cGRlL3BkZXMvcGRlLnB5) | `93.08% <ø> (ø)` | | | [pde/grids/boundaries/local.py](https://codecov.io/gh/zwicker-group/py-pde/pull/315/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group#diff-cGRlL2dyaWRzL2JvdW5kYXJpZXMvbG9jYWwucHk=) | `84.60% <63.15%> (ø)` | | | [pde/tools/mpi.py](https://codecov.io/gh/zwicker-group/py-pde/pull/315/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group#diff-cGRlL3Rvb2xzL21waS5weQ==) | `82.53% <84.90%> (+22.53%)` | :arrow_up: | | [pde/grids/base.py](https://codecov.io/gh/zwicker-group/py-pde/pull/315/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group#diff-cGRlL2dyaWRzL2Jhc2UucHk=) | `89.30% <90.00%> (+0.53%)` | :arrow_up: | | [pde/grids/\_mesh.py](https://codecov.io/gh/zwicker-group/py-pde/pull/315/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group#diff-cGRlL2dyaWRzL19tZXNoLnB5) | `94.92% <100.00%> (ø)` | | | [pde/solvers/explicit\_mpi.py](https://codecov.io/gh/zwicker-group/py-pde/pull/315/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group#diff-cGRlL3NvbHZlcnMvZXhwbGljaXRfbXBpLnB5) | `91.54% <100.00%> (+3.87%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zwicker-group)

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