Table.from_numpy crashes on Inf values

[nikicc]

Orange version

3.8.0.dev0+301d13a

Expected behavior

One can create Table with from_numpy that contains infinity values.

Actual behavior

ValueError Array contains infinity. is raised in _check_arrays, not really sure why.

Steps to reproduce the behavior

Pass numpy array with inf values to Table.from_numpy

Additional info (worksheets, data, screenshots, ...)

[astaric]

Do we really want to allow inf values in X/Y? IMHO they should be converted to nan (=unknowns) before the table is constructed.

[janezd]

I agree with @astaric. A table with inf values is a corrupted table.

[nikicc]

When calculating new features out of existing ones, np.inf is not really the same as np.nan.

But if we don't support them, I will convert them to np.nan.

[nikicc]

An argument for this is that ScatterPlot seems to be handling inf values (#2709).

[ajdapretnar]

This need to be resolved. I vote for converting inf to nan. @lanzagar @BlazZupan if you agree, let us propose a solution so someone can implement this.

[lanzagar]

I don't see enough benefit in supporting inf values for the amount of problems I expect we would encounter in various widgets, at least for now.
I think converting to nan is the most practical solution.

[janezd]

Decision (by @lanzagar, @janezd and @janezd): we change infs to nans.