Get defaultColumn meta to mix in with custom column meta

[martinpengellyphillips]

👋 I was expecting the defaultColumn.meta object to be mixed into any custom column meta definition, but it seems that is not the case. As a workaround I was going to mix them myself when rendering the table.

But how do I access the defaultColumn.meta value from a header context as I couldn't see a public method/property exposed (e.g. there is only header.getContext().table._getDefaultColumnDef).