exporter mapping dimension options look a little anti-intuitive

[nnhjy]

In the docs, the entity dimension is said to specify "the maximum number of entity’s dimensions that the mapping is able to handle." It also seems like a filter for entities based on the dimension.

When a user sets it to 0, the preview filters out all 1-dimensional entities. Nice to have.

Then the user tries setting the dimension to 1. The preview table shows all multi-dimensional entities but excludes the 1-dimensional ones. (Whoops!) And there is no difference in the preview table as the user increases the dimension number to see what is happening.

I suppose it could be more intuitive if the preview table also filters out the entities of dimension no larger than the number put in the entity dimension setting. And 1-dimensional entities should also appear when entity dimension is 1 (before we resolve the ambiguity problem (#2814) from the legacy objective classes).