Always run mpl comparison (currently it's only run when --mpl is set)

[velle]

I expect the current design was chosen for a reason, but I don't quite understand. Please help me understand :)

Why is enabling pytest-mpl image comparison is not the default? Ie why is it only enabled when explicitly setting the --mpl flag?

Why are pytest-mpl tests logged as passed when the image comparison is in fact skipped?

I expect that just typing pytest is enough. I expect that this will run all tests, except some that are skipped because they can't be run, or don't make any sense to run, in the given context.

The current design carries a risk of the user incorrectly believing that all tests passed, when he in fact only executed a subset of the tests.