reproject on a dataframe doesn't work sometimes

[asinghvi17]

reproject on a DataFrame doesn't work if the geometry column is not the first column, since it calls _is3d, which calls _is3d(first(first_row)). This is a problem, that we didn't notice till now because the geometry column was always first in dataframes.

The solution is to amend _is3d with some method on tables. However, it won't be generic, since a table might have 2D and 3D geometry.

Still, it's more important to get it working for now...

[rafaqz]

Ah that's a bug in _is3d that got through tests because we put geometry in the first row